Archive of Our Own

They came from several universes away, using the technology from each planet they visit to construct a vehicle capable of transporting them to other planets. They scour each universe in search of specific planets. 

Planets with water; Planets capable of supporting life. 

Over billions of years they evolved and developed ways of adapting to nearly every possible environment in search of one thing: a breeding ground. A place where they can use the planet’s lifeforms to continue the existence of their own species. They searched world after world, looking for intelligent life. They use their hosts’ genetic material to fill in the gaps in their own, therefore their preferred host species should be intelligent enough to have the technology their offspring will need to leave the planet, and also be strong enough that they can pass that strength and resilience on to their offspring as well. 

After years of searching, they finally found a planet with everything necessary for their reproduction. Lacking any true reproductive organs of their own, the species relies on their host to provide what is necessary for the creation of new life. They need an area surrounded by water for their spawn to have any hope of survival. As luck would have it, there was a rather densely populated island surrounded by a mineral rich ocean on this planet. Surely they could find suitable hosts here. 

After days, the mates finally found potential hosts that caught their attention. They were already engaged in a mating ritual, attacking each other with such beautiful violence as was typical for their own species. They scanned the lifeforms to find that one possessed above average strength for the species while the other seemed to be nimble enough to handle the mating process with the bonus of possessing above average intelligence for the species. 

They were in agreement. 

They were perfect in every way. 

All the parasites had to do was make a few minor adjustments to their biology, and then they could begin. 

…~-~... 

Izaya practically collapsed at the door of his apartment, completely spent from several hours trying to escape from Shizuo. He unlocked the door and stepped inside, considering whether or not he should take a nap as he took off his shoes and coat. As he went to hang up his coat he froze. 

There was… something clinging to the back of it. 

That was the only way he could describe it. It didn’t look like anything he’d ever seen before, and it wasn’t until it moved just a fraction that he realized this thing was alive . 

He stepped back, refusing to take his eyes off the creature as he attempted to analyze what it could possibly be. He found it strange that he hadn’t noticed the thing clinging to him. It must somehow be incredibly lightweight despite its size. 

It was either black or transparent (being difficult to discern as it was blending in with his coat), with vertical stripes on the outside and a cluster of spots in the center that looked to be under its skin. The spots and stripes seemed almost bioluminescent, shifting between colors in a way that Izaya’s mind could barely comprehend, as if the actual color of the spots and stripes were outside the range of human vision. 

Its body was slug-like with several nodules forming bumps down the sides of its body. The outer edges of the main body flattened out into ruffled edges almost like that of oceanic flatworms, with a somewhat triangular end that could be its head, though he couldn’t see anything resembling eyes or a mouth to indicate such. There was a sort of strange antennae looking object on that triangular part that almost reminded him of a snail’s eye stalk but without an eye. Its body was shifting in place, expanding and contracting as it adjusted its grip on his coat. 

What should he do? Should he throw it outside? Try to contain it somehow? He still couldn’t wrap his mind around what it even was . It didn’t look particularly threatening, but looks could be deceiving, right? 

He didn’t have the chance to decide. 

In the blink of an eye the thing moved, dropping from his coat and slithering in a snake-like movement as it approached him at an alarming speed that didn’t seem possible for the shape of its body. Izaya went for his knife only to immediately remember that it was in his coat. Instead he attempted to dive to the side, but that effort had been futile. 

With lightning speed, a white tentacle shot from the front of the creature and caught his hand. The instant it made contact, extremely fine tendrils began to branch out and spread into an almost web-like pattern, shooting up his arm under his shirt and spreading over his chest. He could feel them, cool and sticky against his skin, rapidly spreading over him as if mapping out his body.

Izaya shouted, desperately trying to shake the tendrils off, grasping them with his free hand and pulling hard. They came free where he pulled on them, but they had already expanded much too far for him to be able to remove all of the tendrils with one hand. 

He knew he was alone in his apartment, but he still tried to scream for help… 

Only the sound didn’t get the chance to leave his mouth. His shout died before it even began as he felt a jolt of something cold originating from the tendril followed by an immediate paralysis that instantly took hold of him. He dropped to the ground, unable to speak, barely able to breathe as the body of the creature approached, eventually settling to sit on his chest. The tendrils continued to map out his body, expanding all the way from the top of his head to his feet. They went everywhere . Izaya felt sick to his stomach when the cool, sticky tendrils found his dick, then wrapped around his testicles and began lightly pushing against his anus. 

He had never felt so violated in his entire life. He felt the tendrils carefully worm their way past the ring of muscle, so thin the only way he knew his hole had been breached was because of the cool feeling that was now extending inside of him. 

Panic took over, but he couldn’t move. His chest heaved as the tendrils continued exploring, some now feeling deep into his nose and down his throat, into his ears… As they approached his eyes Izaya realized he could still blink. He shut his eyes tightly, and to his relief the creature seemed to back off. He wondered if it could recognize that touching his eyes the way it was touching everything else would damage them. 

Then all at once, the tendrils retracted. 

Izaya was able to release a shaky breath of relief which immediately became his downfall. The creature took swift advantage of his open mouth, one of the parts that looked like an eye stalk growing in thickness and extending like a tentacle straight down his throat while a sweet tasting liquid shot from the tip. He tried to spit it out, but the paralysis combined with the tentacle pushing deeper prevented him from doing anything beyond accepting his fate as this creature pumped a whole lot of something into his stomach. 

He gagged, but for some reason his body wasn’t letting him vomit out whatever he was being forced to drink. Was that caused by this creature too? The thing was changing shape now, several more tentacles forming from the nodules around the edges of its slug-like body until it resembled something more like an octopus. The monster then used those tentacles to begin ripping at his clothes with a horrifying amount of strength for such a small creature. First was his shirt, then the thing tore his jeans right off of his body…

Then it tore his boxers.

Tears formed at the corner of his eyes as this monster stripped him bare. He didn’t know what it wanted. He couldn’t even attempt to ask with the tentacle in his mouth. He didn’t even know if this thing would understand him even if he could talk to it. 

That’s when something strange came over him. 

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A tingling feeling was rapidly spreading over his body and he could feel his heart rate slow as a wave of calm originating from his core began to spread over him. The moment that feeling reached his head he relaxed, feeling any traces of fear begin to slip away as his mind went almost entirely blank. He was okay. He was safe. Everything was going to be fine. 

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A warmth began spreading from his stomach. A comforting warmth that also left his skin feeling extra sensitive. Every inch of him felt alive and every touch sent a pleasurable sensation down his spine and straight into his cock. 

Submit. 

In seconds he was hard. Whatever this thing had forced him to swallow was messing with his head, and suddenly he was extremely turned on. He forgot all about the horror of the situation he was in and now all that mattered to him was being able to cum. He moaned around the tentacle down his throat, suddenly enjoying the feeling of that liquid filling his stomach and the undulating of the creature on his chest. He sucked greedily on the tentacle, trying to get more of the nectar that made him feel so good. 

Feel.

Submit. 

When he finally relaxed completely, eyes unfocusing as he stared off at nothing in particular while he sucked on the thick tentacle in his mouth, the alien parasite finally set to its real work. 

The creature slid itself down his stomach and rested between his legs, climbing onto his groin. Izaya’s hips bucked up to meet it, the paralysis was already wearing off but he had no desire to try and escape anymore. A slit on the bottom of the creature spread open, swiftly swallowing Izaya’s cock whole down to the base. 

Izaya let out another drawn out moan, eyes rolling back and toes curling at the feeling. The alien then began to undulate rhythmically, something inside the creature creating a sensation similar to several long tongues licking up and down over his cock, bringing him closer to the edge with every stroke. He was panting heavily now, hips thrusting in time with the creature’s stroking. Drool spilled over his lips around the appendage in his mouth as he continued trying to earn more of that mind-melting liquid. 

The moment he felt himself begin to tip over the edge, a soft but firm appendage slick with some type of slime extended from under the slit that had engulfed his cock and slid itself into Izaya’s hole, filling him up perfectly. 

Izaya exploded inside the creature, waves of pleasure like nothing he’d ever experienced before flowing across his body while the alien continued to suck, now also pressing hard against his prostate. Izaya screamed around the tentacle in his mouth as the creature continued milking him through his orgasm, drawing it out long past what a human would normally be capable of feeling. 

The creature then cooed softly in approval. Its chosen host had finally succumbed to the pleasure and was now completely at the parasite’s mercy. The process of joining could now begin. 

Pupils blown, skin tingling, cock harder than ever, Izaya shivered in pleasure as the creature on his cock continued sucking and the tentacle continued its assault on his prostate. He was completely gone at this point, entirely out of his own mind, all defenses stripped away as the creature continued to have its way with him. All that mattered to Izaya was cumming again. And again. And again. 

It was all he wanted. It was all he was good for right now. It made him happy. 

Feel. 

Submit.

Breed.

He could move now, but instead of fighting the creature off, Izaya flipped over onto his knees, lifting his ass into the air. The position allowed the parasite better access, pounding itself relentlessly against Izaya’s prostate now. It too was beginning to grow more sensitive, every movement of the tentacle over it sending a jolt straight through his cock which continued dribbling cum almost constantly as the creature continued to suck. 

The parasite continued until he was completely milked dry, limbs shaking from the strain and exhaustion. Not only did this help to discover the physical limits of its chosen host’s body, but the creature also got its own form of enjoyment from the process. Something that a human might equate to “fun”. Not only that, but it also served a purpose to the process. By pushing its host to its breaking point, the parasite could be entirely sure that its host was ready for the next step. 

When the tentacle in his mouth and ass were removed, Izaya let out a small whine of disappointment. Despite his complete and total exhaustion, all he wanted was more. He was completely drunk off of the creature, not even aware of his own name. Not even aware that he was human. 

Just how the parasite needed him. Submissive. 

Compliant. 

Gently, the parasite positioned itself. Its body elongated to approximately the length of Izaya’s spine, sliding up Izaya’s back and flattening itself out with its triangular head resting between his shoulders just below the nape of his neck with the rest of its body aligning with his spine. From there, the white tendrils from before began to splay out across his back in all directions. Izaya didn’t feel any pain as the parasite’s tendrils became almost microscopically thin and penetrated his flesh. The only thing Izaya felt was a comforting warmth as the parasite slowly entered its hosts’ nervous system. 

A few minutes later, they were finally one. 

…~-~... 

Shizuo returned home, defeated after losing track of the flea yet again. The bastard always found a way to escape unharmed, much to Shizuo’s endless frustration. He'd spend the past few hours wandering the city in an attempt to calm down before returning home, defeated. Mumbling to himself as he entered his apartment, Shizuo decided to head right into the shower, haphazardly tossing his clothes off to the side before slamming the door of the bathroom behind him. 

When he finished washing, he spent some time under the hot water hoping that the heat would help him relax. It was short lived however, when a loud thump from his living room caught his attention. 

Shizuo threw a towel around his waist as he stepped out of the shower, cautiously making his way out into the living room. Of all the things he expected, he didn’t expect to see Izaya. 

He was on the floor, gradually stumbling back to his feet as if he were drunk. The flush on his face also added to Shizuo drawing that conclusion. 

“Hey, Shizu-chan,” Izaya slurred, “I’m glad I found you.” 

“How the fuck did you get in here, flea?” Shizuo asked. 

Izaya made a lopsided shrugging motion. “Picked the lock, ‘course.” 

“Are you fucking drunk?” 

“Drunk? No,” Izaya laughed, “No, no, not at all. Jus’ had to come find ya ‘s all.” 

Shizuo sighed. “Yeah, you’re drunk. How did you manage to get shitfaced so fast, you asshole. You a lightweight or something?” 

Izaya responded with a chuckle, stumbling forward. Shizuo took a step back, trying to keep his distance, but Izaya tripped, falling forward. Instinct took over as Shizuo reached out and caught him before he hit the ground. He grimaced at his reflexes for that. Should've let the idiot hit the ground. 

“Haaah, sorry, I guess ‘m still gettin’ used t’ it,” he slurred, looking around, “Hey, where’s yours?” 

“What the fuck are you talking ab–” Shizuo stopped mid sentence as his eyes met Izaya’s. Now that he was closer, he could see there was something wrong with them. Izaya had brown eyes, but right now they almost looked like an oil slick, subtly shifting between colors in a way that shouldn’t be possible. 

He immediately thought of Saika. That weird sword with a mind controlling ability. But the people he’d seen under the influence of that sword had distinctly red eyes. Was this something similar? A different type of sword? 

Shizuo didn’t have any more time to speculate. Izaya pressed closer to him, letting out a low moan as he bucked his hips against Shizuo’s groin. Shizuo froze on the spot when he realized Izaya was hard, leaving him completely open when Izaya leaned up to seal their lips together in a messy kiss, tasting the remnants of some sweet flavor he couldn't place in his mouth. 

Shizuo gripped Izaya by the shoulders, pushing him back to hold him at arm's length. “What the fuck is wrong with you, Izaya?” he shouted. 

But Izaya was distracted, looking at the floor behind him. “Oh, there it is,” he said with a light smile. 

Shizuo turned to see… something . 

Whatever that thing was crawling along the floor of his apartment, it wasn’t anything he’d ever seen before. He was about to shout, horrified at the way it slithered towards him faster than he could react. In a split second it leapt up at him, a white tentacle shooting out while in mid air, making contact with his bare skin. 

Instantaneously that white tentacle spread out into what was potentially hundreds of small branching tendrils, spreading quickly over his shoulder where it latched on. The thing’s main body slammed itself against his bare stomach with a wet sounding slap. 

“What the fuck?!” Shizuo yelled, grabbing at the creature and yanking it off of his body. It was cool to the touch, it’s body squishy and difficult to hold on to as he attempted to hold it in one hand and pull the tendrils off of him with the other. 

“Don’t worry, Shizu-chan,” Izaya said from behind him, sounding more normal now, “It’s only scary for a second, but it will be fine. In fact, it feels pretty good!” 

“What is wrong with you?” Shizuo exclaimed, still struggling against the creature as another white tendril shot out from its body and attached itself to his hip. He hated the way it spread over his skin, as if caressing every part of the skin it touched. Another tendril shot out, attaching to his opposite shoulder. How many of these did it have?  “Would you just help me out here?”

“Sure, sure,” Izaya said happily, stepping around front to take the creature from his hands. 

Good, now he could focus on pulling off these tendrils. 

Or so he thought. 

He was very quickly distracted, watching in horror as Izaya began to snuggle with the creature, nuzzling his cheek against its weird gelatinous body and planting a soft kiss on its strange, triangular shaped head. The shifting colors on the creature flashed pink when he did so, almost as if it were pleased. The scene had shocked him enough that he paused just long enough for the tendrils to nearly cover his entire body. When he snapped out of it he went to begin ripping them off again only to feel a cold jolt through his body. 

He stumbled, his body suddenly feeling weak, panic beginning to take hold as his strength began to rapidly leave his muscles. 

“I think you’re gonna need more for him, my love,” Izaya cooed to the creature, tickling under what could be its chin, “He’s a lot tougher than he looks.” 

“Izaya, what is this? What’s going…” his voice left him next, vocal cords going numb as he crashed to the ground. He tried crawling away, desperate to escape from Izaya and this thing , but the more time that passed, the more the paralysis was setting in. When he realized he couldn’t move at all the reality of the situation began to set in. 

Am I going to die here? 

Izaya knelt down next to him, still holding the creature in the crook of his arm as he used the other to flip Shizuo over onto his back while the tendrils continued their exploration. The sensation of those cool, sticky tendrils shooting up his nose and into… other orifices made him want to throw up. 

Izaya smiled softly as he placed the creature down on Shizuo’s stomach, giving it a couple pats on its head. The shifting colors flashed pink again in response, a small cooing noise coming from the creature. 

“Now, open up, Shizu-chan!” Izaya said cheerfully as he pried Shizuo’s jaw open. 

He was unable to resist as a long tentacle shot up from the creature on top of him directly into his mouth and down his throat. He could taste that same sweet flavor that had been on Izaya’s lips that he couldn’t identify as the tentacle forced its way into his throat. As that sticky liquid pumped into him uninhibited, Shizuo began to feel hot. Along with that growing heat came a tingling sensation shortly followed by the most intense lust he’d ever felt in his life. 

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“That’s it, Shizu-chan,” Izaya cooed, gently running his fingers through his hair, “Just relax, I promise it will feel good.” 

Shizuo’s thoughts began to grow fuzzy. Something in the way Izaya spoke to him was helping him calm down as the paralyzing effect began to wear off. Shizuo moaned into the tentacle in his mouth, unable to focus on anything other than Izaya’s voice and the intense pleasure. 

Feel.

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“You’re doing really well, Shizu-chan,” he praised, “I was a little worried it might not work so well on you, but it seems you aren’t nearly as resistant as I thought.”

Shizuo’s eyes unfocused as he relaxed. He felt the tendrils retract, and much to his disappointment, the tentacle in his mouth slipped out as well. It was then that he was aware of Izaya straddling him. Izaya’s lips pressed against his own in another sloppy kiss, Izaya seeming to be trying to lick up the remnants of that sticky fluid as if he was addicted to it. 

Part of Shizuo’s mind was screaming at him that this was wrong. He should be fighting back. But that final shred of resistance was torn away from him the moment he felt the creature sliding down between his legs, swallowing his stiff cock whole. 

Ahh, right, this is how it's supposed to be. If I just let this happen, everything will be alright. 

Submit. 

Breed. 

The thoughts felt like his own, indistinguishable from himself as the creature’s aphrodisiac took hold. Izaya continued to kiss him, his hips thrusting as he did so, both of them drunk off of the remaining sweet fluid. 

The creature stroked his cock from inside itself as it sucked, causing Shizuo to let out a low moan into Izaya’s mouth. It only seemed to encourage Izaya more as he moaned back. Shizuo barely felt it and barely cared when a tentacle began to press inside his hole, searching for his prostate. It found it rather quickly, pressing and rubbing against the organ as Shizuo neared the edge. 

He tipped over the edge, eyes rolling back as a shudder worked its way down his spine. Between Izaya’s unrelenting kissing and the sensations on his cock and against his prostate, Shizuo released hard, his cock pulsing and shooting the largest load of cum he’d ever produced into the creature that continued stroking him through it. 

When it was done, he felt Izaya climb off of him. Before he could protest, Izaya’s hands were on him again, flipping him over onto his stomach. He barely registered the feeling of the creature climbing onto his back. He didn’t even notice when the tendrils spread over his back, gently worming painlessly into his skin and becoming one with him. 

When the process was complete, Shizuo blinked. He couldn’t see for himself, but his eyes now sported the same oil slick of shifting colors that he had observed in Izaya. He felt drunk, like the world was spinning underneath him as he sat up. He swayed side to side as he looked over at Izaya who was smiling gently with a glazed look in his eyes, cock straining against his pants. 

He felt the way his body was drawn to Izaya. Like some sort of primal need that he had never felt before. His mind was consumed with thoughts of tearing Izaya’s clothes off and taking him right here and now. Izaya licked his lips, clearly thinking the same thing as he gazed into his eyes. 

“Take those off before I rip them off,” Shizuo commanded. 

Izaya compiled. 

Moments later Shizuo was pressing himself inside Izaya’s hole. His own cock was still slick from the creature and Izaya had clearly already been loosened up as well. His cock slid inside Izaya with ease, making both of them moan loudly. 

He didn’t waste any time before he started thrusting, his mind singularly focused on taking that hole and claiming Izaya as his own. He pounded into him, causing Izaya to cry out in pleasure, fingers grasping at him as he searched for something to hold. His hands settled in Shizuo’s hair, tightly gripping it and pulling him down to kiss him. Their tongues rubbed against one another, tasting a strange mix of their own taste combined with the hint of sweetness that was slowly fading away. 

They were completely absorbed in each other. Nothing else mattered to either of them as their bodies continued to writhe against one another. When Izaya finally came, his muscles squeezing around Shizuo’s cock, Shizuo also tipped over the edge. He released inside Izaya, using his body like a tool meant to stroke out every last drop of cum from inside him. Izaya didn’t seem to mind, his own cum dribbling from his cock and his balls pulling up with each pulse to release more. 

When they were done, Shizuo pulled out, finally spent. From the looks of it, Izaya was also exhausted. They took some time to catch their breath. 

“How about we clean up,” Shizuo suggested, “You can sleep here with me if you want.” 

Izaya nodded in agreement, his eyes reverting back to their normal shade of brown. 

…~-~... 

The pair went their separate ways the next morning, each continuing on with their lives as if nothing had happened. They were, of course, fully aware that they were different now. Their connection to the parasites gave them insight into the alien’s purpose including their own role in all of it. They knew they were mates now, and they knew that their bodies would soon begin to change to accommodate what the parasites needed from them. The parasite’s influence allowed them to accept the change in their relationship with ease, preventing them from doing any serious harm to one another, although their battles were largely the same.

They also knew that they shouldn’t let anyone outside of the two of them in on what had happened. In order for things to continue as planned, they couldn’t share their experience or what they were becoming with any other humans. They would still “fight” when they ran into each other, but Shizuo would now intentionally let Izaya escape once things had gone on long enough to keep up appearances. 

Within a week, their bodies had begun to change. Izaya had become attached to the “female” parasite, requiring flexibility, stamina, and a strong core. Izaya’s years of using parkour as a skill to escape from Shizuo had honed these features in a way that the “female” parasite had deemed appropriate for use. Izaya became aware that the alien was now growing a sort of pseudo-womb inside him, given that he lacked a natural place to incubate eggs. Somehow he just knew these things now, as if they had always been fact. He couldn’t really feel the womb, but he knew he had it now and he knew what its purpose was. He also noticed his skin was slightly more elastic than it had been before. It made sense considering he knew his body would have to accommodate holding eggs without causing too much damage. 

On top of this were some other smaller changes. His body now contained specific pheromones that would act as a signal to his mate for when his body would be ready to be bred. As the time grew closer, Izaya found himself gradually becoming unbearably horny as the days passed. His pseudo-womb created its own lubrication, making Izaya’s ass have some similar characteristics to a human vagina, although its other functions remained the same. It was fascinating to Izaya how he could adapt like this. Still, it was slightly uncomfortable when he would begin to get wet while trying to work with a client. His mind was filled with thoughts of lust, and as time went on, he would find himself having to do more work from behind the scenes rather than direct interaction. This way, the moment his work was done he could take the time to masturbate. His orgasms were much more powerful now, and he’d found out that his refractory period was almost non-existent. If he kept going, he could cum multiple times in a row before collapsing in exhaustion. 

Often times the parasite would help him out, extending a tail-like appendage to slip inside him and fuck him to the point of exhaustion. But as his body approached the peak time to breed, Izaya found that he remained unsatisfied no matter how much he jacked off and the tentacle fucking him didn’t fill him nearly as well as he needed to be filled. He could feel a primal urge building inside him that told him he needed to be bred, and there was only one person who could do it properly…

Shizu-chan. 

For Shizuo’s part, he experienced the same understanding of what was happening to him as the changes began. Shizuo had become the host of the “male” parasite. This parasite was affixed to his back just like Izaya’s except Shizuo’s extended two of those white tendrils around his front and over his hips to attach to his cock. The tendrils met just behind his balls, combining together to form a single tube along the bottom of his cock with branching tendrils cupping his balls. 

He also noticed his cock had gotten slightly longer and a bit thicker as well. Nothing entirely massive, but as breeding time grew closer, a large swelling began to form at the base whenever he got hard. Every time he came (which was increasing in frequency as the days went on), Shizuo noticed the knot grow just a bit more until it was about the size of a baseball. He also noticed small, marble size eggs beginning to form inside the parasite on his back. He knew that the tendril on his cock was the alien’s ovipositor and once his eggs were implanted into his mate’s womb, he would be able to then fertilize them. 

He was becoming unbearably horny, to the point where he was starting to struggle to hide it at work. He knew he’d have to be careful not to let Tom or Vorona realize something was off. They were already somewhat suspicious at his sudden decision to quit smoking, a result of the parasite sending a jolt of panic through him when he tried to light one for the first time. 

After a few days of struggling to get through the day and act normal, he finally caught that scent in the air.

Shizuo glanced up in the direction of the scent to see Izaya standing on the other side of the street, a wicked grin on his face. Instantly Shizuo’s body reacted, and the chase began. Tom tried to call after him, but even on a regular day he knew that was futile. Even more so, now that he was being driven completely mad by that wonderful, delicious scent emanating from his mate. It was time. 

Izaya ran as he usually would, except this time the chase became a type of foreplay. The alien’s mating ritual involved violent battles for dominance, and that is exactly what the chase had become. Izaya was sure to sway his hips just right as he ran, pacing himself so Shizuo could keep up without getting too close. It wasn’t quite time for that. 

Weaving through the streets, Izaya led them both towards his apartment, both very much aware of what was to come. Izaya made it there first, rushing for the elevator and pressing the button to close the doors just as Shizuo approached. When the doors closed, Shizuo changed direction and went for the stairs. By the time the elevator doors opened, Izaya had just seconds to unlock his door and open it when Shizuo appeared from the stairs. 

They both paused, both out of breath, both staring at each other with shifting colors in their eyes. A wicked smile formed on Izaya’s face as he slipped into his apartment, leaving the door open in silent invitation. 

Shizuo charged inside, slamming and locking the door behind him. The last thing they needed was the possibility of being interrupted. Bodies crashed together as Shizuo pinned Izaya’s hands above his head and slammed him against the wall, his grip powerful enough to hurt, but not quite enough to injure. Izaya let out a gasp as the wind was knocked out of him, and before he could make an attempt to breathe, Shizuo’s hand closed around Izaya’s throat. He leaned in and sealed their lips together as Izaya squirmed beneath him, clearly turned on by the dominant display of strength.

Izaya was already plenty wet, his hole longing to be filled since this morning, when the lust had initially overtaken him and compelled him to look for his mate. His cock was hard as well, leaking copious amounts of precum and leaving a noticeable wet stain on his underwear. He was already thrusting his hips against Shizuo when the larger man placed his knee between Izaya’s legs to give him a place to rub against. 

With a low growl, Shizuo shifted, one hand still holding Izaya’s hands in place while the other moved from his throat to his hair, yanking his head to one side to bury his face into Izaya’s neck. Izaya shuddered when Shizuo breathed in deeply, enjoying the delicious scent he was producing. He was in heat, and Shizuo was more than ready to help with that. 

Slowly, Shizuo dragged his tongue along the side of Izaya’s neck, tasting him. Izaya squirmed, hips kicking forward as he moaned at the feeling. Izaya tasted just as good as he smelled, and Shizuo couldn’t seem to get enough. His teeth grazed against Izaya’s throat, just under his jaw. Shizuo could feel Izaya’s pulse pounding against his lips as he bit down–not hard enough to break the skin, but enough to make Izaya scream. Shizuo’s hand shot down to cover Izaya’s mouth, muffling the shout as he backed off, sucking at the area. He was sure to leave a mark before he moved on, this time on the side of his neck, closer to his shoulder. He repeated the same motions there, next moving to mark Izaya’s collarbone. 

He could feel Izaya’s legs shaking, his precum and wetness soaking through his underwear and beginning to show through his pants. It only spurred Shizuo on further knowing how much his mate was enjoying himself. 

Izaya’s hands were free now, which he used to remove his jacket, dropping it in a heap on the floor. He was about to begin removing the rest of his clothes when Shizuo decided that was going to take much too long. In an instant, Izaya’s shirt was ripped off of his body, followed by his pants. Izaya wanted to complain, but he could already feel the way his mind was growing fuzzy. Fuck the clothes. All that mattered right now was being filled with Shizuo’s cock. 

All that mattered right now was being bred . 

Shizuo made quick work of his own pants, tossing them aside and letting his cock rest hot and heavy against Izaya’s. Izaya could see the way the white tendrils coated his cock and balls, covering them in an intricate web which left Izaya anticipating the feeling of that texture inside him. The tendrils throbbed in time with Shizuo’s heartbeat as the base of his elongated cock was beginning to thicken into a knot. It was small for now, but Izaya knew it would swell when it was time for him to be impregnated. He licked his lips at the thought. 

“Izaya,” Shizuo groaned into Izaya’s neck, “Fuck, I need to take you now .”

“So what are you waiting for, hmm?” Izaya replied. 

That was all Shizuo needed. Teeth latching onto the side of Izaya’s neck, Shizuo lifted one of Izaya’s legs up and out of the way. The large, blunt tip of his cock rubbed back and forth against Izaya’s ass, teasing it and getting the head nice and wet in the process. With as much restraint as he could muster, Shizuo slowly began to sink inside, feeling the way Izaya’s hole opened right up for him. So ready. So needy. He closed his eyes as that warm, wet hole sucked him in deeper, feeling every twitch of Izaya’s muscles as he readily accepted his cock. 

Izaya threw his head back as that unyielding hardness slid into him. Finally, he was going to be filled up properly. The thought alone had his own cock leaking steadily now, panting breathlessly at the feeling of the bumps and ridges from the tendrils that wrapped around Shizuo’s cock as it slid fully inside. Finally he was full, his own cock freely dribbling cum down the tip when Shizuo paused, fully sheathed inside of him, knot excluded for now. It felt so good. More satisfying than anything he’d ever felt before. He was so wonderfully full, and all he could think about was how much better it would feel once that knot was fully formed and stuck inside. He felt himself tighten a bit around Shizuo’s cock at the thought, which in turn made Shizuo twitch inside of him. 

Shizuo’s hips began thrusting now, shallow at first to make sure Izaya was opening up nicely for him. It was hardly necessary though, Izaya was already completely lost in the feeling of Shizuo’s cock, mouth open and eyes unfocused as he stared at nothing in particular. 

“You like that Flea?” Shizuo whispered against the side of his neck, “You like feeling my thick cock fill you up?” 

Izaya’s response was a garbled moan, clearly far past being able to form sentences. He was completely lost in his heat, his only purpose now was to submit to Shizuo’s cock and take as many loads as possible into his womb. It was good that he couldn’t speak. Now Shizuo could just take him however he wanted and not have to listen to anything other than those beautiful moans. 

Shizuo picked up the pace, feeling the way Izaya tightened around him at the new sensation. He could also feel the way Izaya’s hands began to claw at his back, looking for something to hold on to as he lost himself. Shizuo shifted position again, pulling Izaya’s other leg up so he could wrap them around his hips as Shizuo fucked him against the wall. Izaya held on tight, his fingers winding into Shizuo’s hair as a last ditch effort to find something to keep him tethered. But Shizuo didn’t want that. He wanted him completely mindless. He wanted to fuck him until he forgot who he was. 

His grip changed, grasping underneath Izaya’s thighs and stepping back from the wall. Izaya leaned forward, arms wrapping tightly around Shizuo’s shoulders as Shizuo began walking over to the couch, cock still buried deep inside Izaya. They practically fell onto the couch together, lips locking together once again as he continued thrusting. Izaya’s hands gripped the couch now, knuckles turning white as he held on the best that he could. 

The cock pounding into him was relentless. Izaya could feel himself already tipping over the edge as Shizuo began to thrust faster now. He could feel his limbs shaking as the pressure continued to build. Only when Shizuo’s hand returned to cover his mouth did he realize he was practically screaming as he finally tipped over the edge. 

“So loud,” Shizuo grunted, “Be careful, I don’t want anyone else to hear that voice of yours. That’s just for me.” 

Izaya’s eyes rolled back as he came, muscles pulsing rhythmically as he released across his chest. He could feel his muscles tighten around Shizuo’s cock, but it was different than the way he would have tightened before. He could feel the way his insides seemed to shift slightly with every pulse. Izaya knew that this was the result of his new organs at work. A new organ that was similar in form and function to a human cervix was now shifting itself into place–that place being at the tip of Shizuo’s cock. This “cervix” was much more elastic than a human one, its main purpose being to ensure not a single drop of his mate’s cum would be wasted. The orgasm wreaking havoc through him was the trigger for this organ to begin its work. 

Shizuo felt his cock rub up against something inside Izaya. He knew it was just about time now to officially breed his hole. As the pseudo-cervix stretched around the head and worked its way down his cock, Shizuo felt his knot finally fully come in. Everything in him screamed at Shizuo that now was the time to push it in. He obliged, pressing the large knot against Izaya’s opening and feeling the way it yielded to him, allowing it to sink inside. 

“It’s time,” Shizuo said breathlessly, “Are you ready?” 

Izaya’s response was a wordless, enthusiastic nod. 

Once the knot was in, Shizuo was forced to stop moving and let his body do the rest. He doubled over, moaning loudly into Izaya’s neck as he released. From the white tendril under his cock he could feel small, marble-sized eggs work their way down all the while his cock simultaneously released a continuous stream of sticky, white cum that would serve to fertilize the eggs as they implanted into Izaya’s womb. With every pulse, the tendrils around his cock and balls squeezed and released, forcing as much cum from him as possible. A tentacle-like a tail emerged from the bottom end of the parasite on Shizuo’s back, sliding itself deep inside of Shizuo’s own hole in order to milk his prostate from the inside. 

The process took several minutes as the parasites worked together to ensure that every last drop of cum was extracted from Shizuo’s cock and absorbed into Izaya’s womb. Meanwhile the pair was left lost in the sensation of orgasm, continuously cumming through the entire process, far beyond the length of a normal human orgasm.

Izaya felt the eggs slip inside his womb along with that hot cum that kept gushing out of Shizuo’s cock. For a moment, he questioned how it all fit inside him, his own cock was still cumming, but dry now. His own cum was useless in this process, so the parasites didn’t help him produce much more than he naturally would like they did with Shizuo. 

“Fuck you feel so good, Izaya,” Shizuo groaned, “You're taking me so well.” 

Izaya was shaking now. He was so full from Shizuo's cock, yet somehow his body continued to accept more eggs and more cum. It felt so warm inside him, comforting him in a way that he couldn’t describe. He was so full. So wonderfully full. 

Finally,  Shizuo's knot began to shrink as the final spurts of cum were pumped into Izaya's womb. He shuddered at the relief he felt, finally feeling content after days of being unable to satisfy himself properly. 

Izaya felt similarly, basking in the feeling of being so perfectly full of warm cum and eggs. When Shizuo's cock finally slipped out, he only felt the loss for a few seconds before the parasite on his back produced that tail-like tentacle, stuffing itself into Izaya's hole like a plug. It had to keep all of that precious cum inside him to ensure maximum fertilization of the eggs. The remaining cum would be absorbed for energy by Izaya's new womb. Not a single drop would be wasted. 

A hand rested on Izaya's lower stomach, drawing Izaya's attention to the slight bulge that had formed there–a visual piece of evidence to how full he felt. Izaya's hand joined Shizuo's as they both marveled at their work. 

Shizuo leaned in to gently kiss Izaya again before carefully picking him up and carrying him to the bathroom. After he diligently cleaned them both up, he carried Izaya to bed, curling up around him protectively. Izaya was already fading in and out of consciousness by then, his ass still plugged as it would remain for the next few hours while he rested.

As sleep took him, Izaya could still feel the way Shizuo continued to pepper him with gentle kisses while his hands wandered, lightly brushing over Izaya's sensitive skin. 

  …~-~... 

Izaya sighed as he stared at himself in the mirror. It had been almost one month since Shizuo had bred him, and for those past three weeks Izaya hadn't noticed any major differences. But within the past week, the eggs had suddenly begun to grow exponentially. At the beginning of the week it just looked like he'd overeaten, his stomach just slightly bloated similar to how it had looked when he’d first been bred. But with each passing day, he was growing. 

And now today, he was unable to button his pants around his heavy abdomen. Izaya sighed, choosing to go with sweatpants instead. He would have to avoid being in public for a bit once he really started showing. He couldn’t risk someone he knew noticing the bulge. He wasn't sure exactly when they would be coming, but he knew it wouldn't be too long now. 

Izaya canceled any in-person meetings, choosing to keep things strictly online for now. He also told Namie to take the week off, using the excuse that he had come down with the flu to keep appearances. 

For the next two days Izaya mostly just lounged around, resting as much as he could. The eggs had continued to grow in his womb to the point where they were beginning to press and rub against his prostate any time he sat upright, meaning he had to lie down most of the time unless he wanted to be constantly hard. 

His body had also begun craving more food, but thankfully nothing excessive. He could survive off of what he already had, though he knew he was going to run out of food a bit sooner than he normally would. He could only hope the eggs would come before he was forced to go out. 

It was one day later, late into the evening that Izaya began to feel strange. The pressure on his prostate was constant now, and it was becoming difficult to keep himself from being turned on. But that wasn't what was bothering him. There was something deep down in him that was screaming at him to find water. Not to drink, no, he needed to be in the water. Now. 

His body was telling him to find something like a lake or the ocean, but he didn't have that kind of time. The only thing he could do was fill his bathtub and hope it would suffice. He watched the water fill, his breathing growing heavy as the need became overwhelming. He couldn't wait any longer. 

The tub was only half way filled when Izaya lowered himself down. The instant his slightly distended abdomen hit the water, he felt what had to be a contraction. 

“Fuck,” he whispered, desperately trying to find a comfortable position. He settled on kneeling in the tub, knees spread apart as the contractions continued. 

His body shook with the strain of it when he felt the first egg begin to make its way down. It suddenly occurred to him that he wasn't sure if he could do this alone. Izaya pushed, hands gripping the edge of the tub. The first egg pressed hard against his prostate as it passed over it, causing his dick to start leaking precum into the water as the egg then traveled the rest of the way down. He could feel himself stretch around it as he pushed until finally it popped out into the water. 

The relief was intense, but short lived. Izaya began to pant as he felt the second egg started to move. He wasn't even sure how many there were… How was he supposed to do this alone? Where was his mate? He needed Shizuo. 

A shaky hand found his phone from the pocket of his pants on the ground. He tried to focus on the device long enough to dial Shizuo's number as the second egg passed over his prostate and out into the water. The phone rang while the third egg slid down.

“Hello?” Shizuo answered. 

Hearing his mate's voice immediately triggered a fourth egg to begin pushing out before the third had even been passed. Yeah, he needed Shizuo for this. 

“Shizu-chan,” he breathed, “Please, I'm… they're coming out.” 

“Where are you?” 

“Home, in the tub,” Izaya groaned, “It happened so fast.” 

“It's okay, I'm on my way,” Shizuo assured. 

“Hurry. I–ah! I n-need you…”

“I'm going as fast as I can, but I might not make it there in time,” Shizuo said. 

Izaya whimpered at the thought of having to go through this without his mate. Another egg pushed down against the other two, but he wasn't able to get them to push out. The first one must be larger, blocking the other two. They rubbed against his prostate as he pushed, his cock dribbling cum despite the pain.

Tears pricked at the corners of his eyes as he pushed. “Shizu--chaaan,” he groaned, “I can't–I think they're stuck.” 

“It's okay, you can do this,” Shizuo reassured, “I might not be next to you, but I'm here. Just breathe.” 

Izaya did his best to listen to Shizuo's advice, taking a few deep breaths. One more deep inhale and Izaya pushed again. He could feel the way his hole stretched around the stuck egg, reaching down to see if he could help pull it out. 

He placed the phone on the sink on speaker so he could use both hands. With one more push, Izaya cried out as all three eggs popped out in rapid succession. Izaya gasped for breath as he came, the feeling of the eggs finally forcing their way out sending him over the edge. 

“Ahhhhooooooohh~” Izaya moaned as the next eggs worked their way down, refusing to give him any time to rest. 

“Izaya? Are you okay?” Shizuo asked, sounding panicked. 

“Y–ahh! Yeah,” Izaya managed to say breathlessly, “I think the last ones are coming now.” 

“You're doing great, Izaya,” Shizuo encouraged, “Just a little more. I'll be there to help soon.” 

Izaya grit his teeth. He knew Shizuo wasn't going to make it on time, but at least he would be there for him when it was over. He would have to be better prepared next time. He couldn't imagine going through this again without the help of his mate. 

When the last few eggs finally came out, Izaya sagged into the tub, allowing the warm water to sooth his aching muscles. There were ten eggs in total, sitting at the bottom of the tub. Izaya was finally able to get a better look at them, noticing the way they glowed slightly, shifting colors to indicate they were all healthy. They were larger than a regular chicken egg, but the largest was a bit larger than a baseball. 

He stayed with them until Shizuo arrived, entering with the spare key he now had. Shizuo did what he could to comfort Izaya, holding him close and whispering words of praise at how well he’d done by himself. They knew the eggs couldn’t stay here though. The following morning they brought the eggs to the ocean, releasing them in a secluded area away from prying eyes. 

…~One month later~...

“Shizuo, are you alright? You seem distracted today,” Tom pointed out. 

“Agreed. Shizuo-senpai has been acting strange,” Vorona added. 

“I’m fine,” Shizuo assured, realizing he’d have to be more careful, “I guess I’m just not feeling well.” 

“That’s unusual for you,” Tom said, sounding concerned, “Do you need to take the rest of the day off?” 

“Huh? Oh, yeah,” Shizuo nodded, “Actually, if that’s okay I think I might.” 

Barely ten minutes later Shizuo parted with his coworkers. It was for the best, he decided. How on earth was he supposed to work with that scent in the air? It had taken all of his focus to keep himself from getting hard every time the wind changed direction, that beautiful scent of his mate in heat wafting through the air. 

He could tell Izaya wasn’t far away. When he followed the scent, he realized it was leading him towards his own apartment. The closer he got, the stronger the scent. 

When he burst through the door of his apartment the scent was overwhelming. Izaya was here for sure. Shizuo rushed to where the scent was strongest, in his bedroom. He opened the door to find Izaya naked on his bed, his hard cock in one hand and one of Shizuo’s shirts in his other, pressed against his nose as he moaned. 

“Sh-shizu-chan,” Izaya whimpered, stroking his cock faster, “F-finally. Please, I n-need you,” 

“Damn needy bastard,” Shizuo grumbled, already removing his own clothes, “I could smell you all fuckin’ day. You think you can tease me like that and get away with it?” 

“Mmmm, maybe I don’t w-want to get away with it,” Izaya moaned, “H-had to fight the urge to find you on the st-streets or else I don’t think I w-would have been able to control m-myself.” 

Shizuo was on top of him in seconds, situating himself between Izaya’s legs and gripping his hair to keep him still while he used the other to pin Izaya down by the throat. 

“Oh, I’m going to ruin you,” Shizuo growled into Izaya’s ear, teeth grazing over it as he spoke, “I’m gonna make that hole remember the shape of my cock as I breed you.” 

Izaya’s eyes shifted colors rapidly as Shizuo spoke, his pupils dilating as the words sunk in. He had been practically insane with need all day, unable to satisfy himself even a little bit. Shizuo’s words were enough to make him forget everything. He needed that cock pounding into him and he needed it now . 

“Fuck I love it when you squirm like that, flea,” Shizuo continued, “Want my cum that badly, hm?” 

Izaya nodded helplessly, though his movement was restricted by Shizuo’s grip. 

“Good boy,” Shizuo pressed their lips together while his cock began to rub against Izaya’s ass. 

He could tell Izaya was already wet for him, but the way that hole immediately gave in under the press of the head of his cock told Shizuo exactly how powerful Izaya’s heat was this time. There was barely any resistance as the head popped inside, and Izaya was left a mewling mess as he desperately tried to impale himself on Shizuo’s cock. 

Shizuo quickly put a stop to that, grabbing hold of Izaya’s legs and pulling the head back out while he whined in protest. Before Izaya could complain any more, Shizuo grabbed hold of his arm and flipped Izaya over, hands grasping Izaya by the hips and pulling him into position. Izaya picked up on what was happening, immediately spreading his legs to give Shizuo access. 

Using one hand to guide his cock, Shizuo finally began to press himself inside that warm, wet heat. Shizuo closed his eyes as he sank inside, feeling the way Izaya so readily sucked him in unlike anything he’d experienced before. This hole was his to take, and he knew nobody else could satisfy Izaya the way he could when he finally released his eggs into him. 

The anticipation was beginning to drive him mad as he began lazily thrusting himself into Izaya, who was already a complete mess. He could see the trail of cum leaking from the tip of Izaya’s cock onto the bed as it began to flow almost constantly. He wondered how many times he would be able to make Izaya cum tonight. 

Izaya pressed his face into the crook of his arm as Shizuo took him, one hand stroking himself in time with Shizuo’s thrusts. It felt so incredibly good to be finally filled, but what he really craved was that knot. He knew he couldn’t be satisfied until he felt that knot lock them together and fill his womb with eggs and cum. 

Just the thought of it and Izaya was cumming, moaning loudly into the pillow beneath him as cum shot from his cock onto the sheets below. His muscles tightened around Shizuo’s cock with every pulse, but Shizuo’s pace didn’t slow. The relentless thrusting had Izaya already reaching a second orgasm only seconds after the first had finished, his overly sensitive nerves going into overdrive as he completely lost himself in the pleasure. 

Shizuo felt his knot growing already, but he wasn’t done with Izaya yet. Izaya’s hand had already fallen away from his own cock, now gripping the sheets as he tried to hold on to consciousness. Shizuo took the opportunity to reach his own hand around and began stroking. 

Izaya practically screamed into the pillow, his overstimulated nerves pushing him towards a third orgasm as Shizuo stroked him. It was all he could do to just keep holding on. He was completely at Shizuo’s mercy when he came again, tears beginning to fall from the sheer intensity of the sensations his body was experiencing. 

It was then that he felt that familiar shifting inside. His body was ready for eggs. 

Shizuo’s knot was fully formed now, and he was no longer able to resist the urge to press it inside. Izaya’s hole stretched around him as he forced the knot inside, finally locking around him and holding him firmly in place, unable to pull out even if he tried. The head of his cock was nestled just inside Izaya’s cervix, perfectly placed to make sure nothing was wasted. The tail-like tentacle from the alien on Shizuo’s pack slipped inside just in time for when Shizuo finally tipped over the edge, biting down on Izaya’s shoulder as the tendrils around his cock and balls began to squeeze and release in time with his orgasm. He held still as he felt the eggs push into Izaya along with his cum, happy that he could finally breed him properly. 

Shizuo slipped out of Izaya to admire his work. Izaya was breathing heavily, ass still in the air as the alien’s tail-like tentacle extended out to plug him up just like last time. 

Except this time was different. Instead of plugging him, the tendril began to thrust in and out, refusing to let Izaya rest just yet. Izaya moaned, still extremely sensitive as that tentacle shoved itself into him. He was still hard, cock somehow still leaking as his hole was assaulted once more. 

Shizuo stared in awe at the way Izaya’s body writhed under the attention, noticing the way the tentacle then began to focus on Izaya’s prostate. His eyes rolled at the feeling, moaning and panting as the tentacle continued to fuck him. Some cum was leaking out, dripping down his thighs as he was fucked, leaving Shizuo feeling as if he should probably replace the lost cum with more. But for a while he just watched, amazed at Izaya’s stamina as he came yet again. How many times was it now? Shizuo had lost count. But Izaya looked so beautiful like that, completely lost in pleasure and making the most heavenly sounds. 

Before he knew it, Shizuo was stroking his own cock at the scene. Somehow despite already having laid his eggs, he was getting hard again. He could feel the way more eggs began to work their way down to the tendril on the underside of his cock. He was quickly overcome with the urge to breed again. How could he not? Izaya was so swollen with eggs and cum, yet there he was with his ass up in the air just begging for more.

“I think they’re trying to tell us you can handle more, don’t you think, flea?” 

Izaya’s only response was a cry as the tentacle forced him to cum once again. There was barely anything left this time despite the intensity remaining the same, Shizuo noticed. He’d be completely spent soon. He’d better hurry. 

He repositioned himself at Izaya’s hole and the tentacle tail retracted, giving him access. Shizuo didn’t waste any time pressing back inside, feeling the way Izaya’s hole opened right up for him while Izaya greedily pushed back against his cock. 

“Think you can fit more in there?” 

“M-more,” Izaya breathed, barely able to speak. 

“Shit, you’re really into this, huh?” 

“Mmmmahhhh~!” Izaya moaned, drooling on the sheets beneath him. 

Shizuo had to admit it was hot to see Izaya like this, the silver tongued informant reduced to nothing but moans and heavy breathing as he came over and over again from Shizuo’s cock. His heat must have been intense this time for him to be this needy. Shizuo would have to make sure his mate was truly satisfied this time. 

He began moving his hips, taking Izaya once again at a steady pace. Izaya’s moans spurred him on, encouraging him to really let loose. He could feel the eggs pressing along the underside of his cock, rubbing against Izaya’s inner walls. The combined sensations making Shizuo’s mind go numb. He just wanted to keep fucking that hole. His hole. Everything else faded away as his mind was filled with the singular thought of breed, breed, breed . 

Meanwhile, Izaya was enjoying the different textures of Shizuo’s cock, especially the way the eggs rubbed against him, teasing him with what was to come. He too was completely enthralled with the sensations that threatened to completely break him. He had never cum so much at once before, and he could feel the way his mind was being taken over by it all. Some part of him, way deep down, was alarmed at the feeling, but it was quickly overtaken when the parasite on his back released a chemical to calm his mind, reminding him to submit. 

For the next few minutes, Izaya Orihara was gone. Floating somewhere between consciousness and total black out. Forgetting that he ever existed outside this moment in time as his limbs became jelly. He was only vaguely aware when Shizuo knotted him. Only vaguely aware of that shifting inside of him as his body did the work necessary to accept Shizuo’s eggs. Izaya came one final time as Shizuo’s eggs slowly popped inside, one at a time, followed shortly by the cum that would fertilize them. 

It was too much, and yet at the same time it was not enough. The parasites had pushed him too far. 

Izaya blacked out. 

…~Three Weeks Later~... 

Shizuo sat anxiously on the train, checking his phone every few minutes to see if there were any updates. Izaya had left for the new lake house property a week ago, unable to freely move around Ikebukuro now that he was looking visibly pregnant. He had started showing much sooner this time and he had complained about it, saying that he would draw too much attention, especially if someone they knew spotted him like that. 

Still, Shizuo couldn’t up and leave the way Izaya could, so he had to plan more carefully. He was relying on Izaya’s experience last time to make sure he could arrive in time to help, but with things being slightly different this second time he was anxious. 

Izaya was already larger than he had been before. Obviously that was because he had more eggs this time, but Shizuo couldn’t shake the feeling that maybe that would change the gestation period this time. Izaya seemed pretty confident that it would be the same, and was sending updates as often as possible to help reassure him. 

When he finally arrived at the lake house in the countryside, he didn’t even take time to enjoy the beautiful view. Instead, he went straight inside to check on Izaya. He found him lounging on the couch, looking mostly relaxed, but slightly uncomfortable. 

It made sense he’d be experiencing discomfort now that Shizuo got to see him. His abdomen had the appearance of being about six months pregnant, and considering the most growth happened in the final week, Shizuo was sure he would be bigger over the next few days. Maybe not quite to the size of a human pregnancy, but neither of them could be sure of that. 

Still, all of this was clearly hard on Izaya’s body. With each passing day Shizuo did everything he could to make sure Izaya got plenty of rest, and was able to eat nutritious food. Everything Izaya needed to ensure he was in the best condition possible when the time came. He even helped out when the eggs began to press against Izaya’s prostate as they grew, laying Izaya in his lap and lazily stroking his cock while they relaxed. 

According to Izaya, this stage had come sooner due to the amount of eggs inside, though he didn’t think it meant they were coming sooner. In the end, he was right. It was a long final week for Izaya, who spent most of his time in a constant state of stimulation from the growing brood. It got to the point where he didn’t even have to touch himself and instead was cumming just from the act of moving around the house. 

It was the dead of night when the time finally came. They were asleep, wrapped in each other's arms when Izaya suddenly bolted upright, wide awake. 

“Shizu-chan,” he whispered, shaking Shizuo awake, “It’s starting, we have to go.” 

Shizuo leapt out of bed and quickly scooped Izaya out of bed. The last thing he wanted was for Izaya to have to walk all the way down to the water in his current state. 

Izaya gripped tightly onto Shizuo, feeling the contractions growing with every passing second. The instant he laid eyes on the water Izaya groaned. The eggs seemed to somehow sense the water was near, the first egg already starting to force itself past his cervix. 

Seconds later, they were in the water. It was cold, but the chill was welcome for Izaya who was already working up a sweat. Thankfully they’d only been wearing their underwear to bed, and Shizuo made quick work of helping Izaya remove them. 

It was just in time too, the first egg already halfway out the instant Izaya’s skin touched the water. Izaya held onto Shizuo like a lifeline, limbs shaking as the first egg popped out. Immediately, two more worked their way down together, pressing hard against Izaya’s prostate as they moved. 

“It’s okay,” Shizuo said soothingly, “I’m right here, you’re doing great.” 

“Fuck,” Izaya whispered breathlessly as the two eggs popped out in rapid succession. 

Not only were there more this time, but they were bigger. The first three were already close in size to the one that had gotten stuck last time. Maybe it was Shizuo’s presence that made it easier this time. Maybe it was the help Shizuo had been giving him all week. Either way, he was thankful. 

That said, he knew this was still going to be rough. 

He continued pushing, his cock already hard from the pressure on his prostate. Three more eggs forced their way out, causing Izaya to shudder as he came. Izaya felt himself growing weak at an alarming rate. The larger size of the eggs was already giving him a rather hard time, but he knew there were so many still left inside. He could feel them every time he shifted his hips to try to find a better angle. 

“Keep pushing, Izaya,” Shizuo whispered, lips pressed against his temple, “And remember to breathe.” 

Izaya pressed his head into Shizuo’s shoulder while his hands tightly grasped Shizuo’s hand. It was a good thing Shizuo was as strong as he was, because Izaya was sure the grip he had on that hand would hurt a normal person. But it definitely helped keep him grounded as he pushed. 

He was almost fully submerged, the cold water felt good against his burning hot skin. Each egg was getting more and more difficult to pass as time went on, and Izaya was beginning to grow concerned that he might not be able to get the rest out. When a few more eggs made their way out, Izaya finally began to feel some relief. It was short lived, however, when that familiar feeling of an egg getting stuck came over him. 

Shizuo seemed to sense something was wrong, his free hand that Izaya didn’t have in a death grip making its way into his hair. 

“You’re doing so well,” he assured, “Just a little more, okay?” 

Izaya pushed again, crying out in frustration when the egg didn’t budge. He was shaking now, his breath coming in short pants. He was starting to feel lightheaded. 

“Shizu-chan,” he breathed, “I-I can’t–” 

“Yes you can,” Shizuo cut in, “I know you can.” 

“N-no–aahhhh” Izaya cried, tears falling freely as spots invaded his vision, “I’m gonna… p-pass out.” 

“Let me help then,” Shizuo suggested, turning Izaya around so his back was against his chest. 

With firm, but gentle pressure, Shizuo began to press down on Izaya’s lower abdomen. The effect was immediate, Izaya feeling the remaining eggs push down, backing up against the one that was stuck. 

“It’s not moving,” Izaya breathed. 

“Just push at the same time as me, got it?” 

Izaya nodded. 

With one final, massive push and Shizuo’s assistance, the large egg forced its way out, followed immediately by the remaining eggs. Izaya screamed, his voice cracking from a combination of exhaustion and with the force of his climax when they all finally came out. 

“That’s it… That’s… all…” Izaya trailed off as he passed out in Shizuo’s arms. 

The remainder of the night relied on Shizuo. He’d been doing his best to count the eggs, but he wasn’t sure how accurate he was. By his count, Izaya had laid somewhere around 20 eggs. It seemed about right considering the first clutch had been around 10. Still, he couldn’t help but feel proud of how well Izaya had done. 

Carefully, he carried Izaya out of the water and back up to the house. From there, he cleaned them both off, taking extra care to massage Izaya’s sore muscles when he slowly regained consciousness. 

Once they were both clean and dry, Shizuo lowered Izaya back into bed, wrapping him up tightly in the blankets and sliding into bed next to him. He spent the rest of the night with his arms wrapped around his sleeping mate. 

…~Several Months Later~... 

“Excellent work, Celty!” Shinra praised, “Just hold them still for a bit.” 

“What the hell is this all about?!” Shizuo exclaimed, struggling against his bonds. 

Celty had to focus more attention on keeping Shizuo bound than she did with Izaya. Shinra picked up on that and went to examine Shizuo first. 

Celty had known there had been something off with Shizuo and Izaya for a while now. Though she didn’t see Izaya very often, she spent enough time around Shizuo to begin to grow suspicious. If she didn’t know any better, she’d say Shizuo was an imposter. He was still the same in every way, but there was something about his presence that… didn’t feel human lately. 

When she’d tried asking if anything had changed, Shizuo brushed off her concern, assuring her that he was fine. It wasn’t until she met up with Izaya for business and felt the same exact feeling that she finally brought it up with Shinra. It would be one thing if they felt different in their own distinct ways, but no, Shizuo and Izaya were both giving off an aura that was different in the exact same way . 

Shinra never doubted her instincts for a moment. It seemed the pair weren’t going to offer anything when asked directly, so Shinra suggested a trap of sorts. 

And so, Celty invited Shizuo over to their apartment at the same time that Shinra invited Izaya. When they both arrived, Celty used her shadow to subdue them both, holding them still so Shinra could perform an exam. 

“Shinra, what are you doing?” Izaya asked, frantically struggling against the shadows wrapped around him, “Let us go.” 

“‘Us’?” Shinra questioned as he approached Shizuo, “Seems a bit strange for you to be concerned about anyone other than yourself, especially Shizuo.” 

“This is stupid, Shinra, there’s nothing wrong with me,” Shizuo said, though there was a slight panic in his tone that didn’t go unnoticed by the underground doctor. 

“Then why not let me do an exam? If you have nothing to hide, this shouldn’t be an issue.” 

“This is ridiculous,” Izaya spat, that same undertone of panic in his voice. 

“Celty, help me remove Shizuo’s shirt so I can do this properly,” Shinra said, ignoring their protests. 

“No!” they both shouted in unison, causing both Shinra and Celty to pause. 

They glanced at each other, now more convinced than ever that something was wrong. 

“Why so defensive, you two?” Shinra said as Celty tore away Shizuo’s shirt, “You’re really not helping your–ah!” 

Silence hung in the air as Shinra and Celty stared in horrified astonishment at the thing that had just been revealed. 

If Celty had a head, she would have screamed. The strange creature latched onto Shizuo’s back could only be defined as alien in nature. Nothing she had ever seen or heard of before. A shudder tore down her spine at the sight of the creature undulating as if it were trying to hide itself. 

“Celty, let me see Izaya too!” Shinra exclaimed, his tone becoming serious. 

“Shinra, please–” Izaya began, but was cut off when his shirt was torn from his body, revealing a similar looking creature also latched onto his back. 

“What are they?” Shinra asked, moving in closer. All the while, Shizuo and Izaya both continued struggling. 

With a gloved hand, Shinra prodded the creature on Shizuo’s back, watching the way it shimmered with a bioluminescence emanating from where he poked. Up close he could see that this thing had tendrils that embedded themselves into their skin. He pulled at the tendrils, noticing that they had a bit of give, but ultimately didn’t release their hold. The more he messed with it, the creature’s colors began shifting to a red color, as if it were trying to show it was angry. 

Shinra dug through his supplies, pulling out various items to see if he could use them on the creature. He tried cutting them, but they instantly healed when he sliced. He then tried chemicals like rubbing alcohol, peroxide, and even salt wondering if their slug-like form would react to it. 

While there was nothing from the creatures, Shizuo and Izaya seemed to be growing increasingly desperate, now begging the pair to let them go. It was alarming to see them acting like this, making Shinra more curious to find out what exactly these things were. But Celty was beginning to struggle holding Shizuo back, and Shinra was concerned she may lose her grip. 

That’s when he decided to step it up a notch. 

After some searching, he managed to find the modified stun gun Izaya had given Akane Awakusu once to use on Shizuo. He knew the voltage wouldn’t be enough to cause any real harm to Shizuo, so he figured he’d try it on him first. 

He jammed the device directly into the creature on Shizuo’s back, resulting in a loud cracking sound. The creature flashed several colors in rapid succession before going dark. 

“Shinra, stop !” Izaya yelled, but Shinra ignored him. 

“Sh-Shinra,” Shizuo mumbled, breathing heavily, “Oh fuck. H-help.” 

“Shizuo? What’s going on?” 

“I… I can’t… I think you just knocked it out,” he said, panicked, “F-fire! It didn’t like it when I tried smoking!” 

“What is it doing? Is it controlling you?” 

“Not exactly–” Shizuo paused, “Shinra, please, you have to let me go. I promise I’m fine.” 

Shinra blinked, confused until he looked to see the creature had seemingly regained consciousness, colors shifting through reds and yellows. 

He quickly located a lighter, flicking on the small flame. The response was immediate. Both Shizuo and Izaya grew even more frantic, their voices overlapping as they begged. 

“Shinra–”

“I promise we’re fine–” 

“–please put that away–” 

“It’s really nothing serious–” 

The instant the flame licked at the strange translucent flesh of the creature, its entire body turned black. Shinra watched as the tendrils in Shizuo’s skin retracted back into the creature and it fell to the ground. 

“NO!” Izaya screamed, startling both Shinra and Celty. 

Before they could recover, the creature on the ground shot for the nearby window, crashing through and flinging itself to the ground far below. Celty chased, but almost immediately it seemed to disappear, camouflaging itself with the ground and causing Celty to lose sight of it. 

They turned their attention back to the pair. Izaya was now violently fighting Celty’s shadow with a strength she didn’t know he had while Shizuo had gone completely silent. 

“Shizuo?” Shinra said, cautiously approaching. 

“I…” Shizuo whispered, “I think I’m gonna be sick.” 

“Let him go, Celty,” Shinra said, “I think he’s okay now.” 

Celty hesitated, but retracted her shadows. Shinra escorted him to the bathroom, making it just in time for Shizuo to lose his lunch. 

When he returned, he looked much better, albeit shaken. He brought the trash can from the bathroom with him, setting it down in front of Izaya who was still frantically struggling. 

“Go ahead, Shinra,” he said, “It didn’t hurt too bad, I think Izaya can take it.” 

“You sure?” 

“Yeah, it’s just extra freaked out seeing what just happened and it’s making Izaya try to defend it. Trust me, Izaya doesn’t want to be doing this, he just doesn’t realize it yet.” 

Shinra nodded, positioning himself behind Izaya, lighter in hand. 

Izaya wasn’t having it though. He shouted, twisting his body at uncomfortable angles to try to escape the approaching flame. Shizuo took hold of his shoulders, holding him still and looking into his eyes. They were flashing multiple colors in alarm, but he seemed to calm down slightly when he saw Shizuo’s face. 

“It’s okay, Flea,” he said gently, causing Shinra and Celty to exchange concerned glances, “I’m right here, okay?” 

“N-no,” Izaya whimpered, his whole body shaking now. 

“Just breathe,” Shizuo said, glancing at Shinra as a signal to continue. 

Izaya closed his eyes, seeming to accept his fate as the flame approached. Before it even touched, Izaya jolted as the parasite tore itself out of his nervous system. The sudden movement startled Shinra, who jumped back as the alien blended itself in with the ground beneath it and shot out the window following its mate. 

Celty released Izaya, gently lowering him to the ground where he instantly collapsed. He was very still for a moment, breathing heavily as he tried to collect himself. The feeling of being snapped back to his senses was instantly overwhelming the same way it had been for Shizuo. That along with the memories of the past few months was enough to have Izaya reaching for the trash can Shizuo had brought out for him, immediately emptying the contents of his stomach. 

“Fuck,” he gasped, “Oh fuck .” 

“Should we be worried about those things escaping?” Shinra asked. 

Izaya was the one to answer. “They’ve been discovered, so they’ll most likely move on from Earth. Although I’m not sure about the….” Izaya glanced up at Shizuo, their eyes meeting for a moment. “...nevermind. I just want to go home.” 

They came to a silent agreement not to mention the babies given the questions it would raise. With any luck, they would grow up and flee the planet like their parents in search of their own mates. 

…~Six Months Later~... 

“Where are you aiming, Shizu-chan?” Izaya teased, “I didn’t even have to try to dodge that one~!”

“IIIIIIZZZZAAAAAYYAAAAAAAAAA!!” 

As much as they were a nuisance, Celty was pleased to see Shizuo and Izaya acting normal again after that strange event six months ago. It had been absolutely horrifying to learn that aliens were real and that they took such a terrifying form. Celty found herself constantly checking Shinra to make sure he hadn’t been infected with one of the parasites that had gotten away, especially after having recurring nightmares about the situation. She shuddered at the thought before turning around to rush home to her partner. 

Izaya laughed as he leapt over a fence, feeling the breeze through his hair. Shizuo crashed right through the very same fence seconds later, barely noticing the obstacle. They continued their chase well into the night, eventually weaving through alleys until they found themselves away from prying eyes. It was only then that Izaya’s pace slowed, allowing Shizuo to catch up. Shizuo’s hand wrapped around his throat, pinning him against the wall as his lips pressed against Izaya’s. 

The parasites were gone, yes. But that primal attraction had remained, leaving the pair inexplicably drawn to one another. They regularly met up like this now, bodies intertwining as they used each other for pleasure. Most of the time, they would split up immediately after. But sometimes, Izaya would find himself exhausted to the point where he didn’t mind sleeping next to a monster.

… if only due to the promise that the fun would continue the next day.