Archive of Our Own

"Izuku, sweetie," Inko called out as she hung up the phone. "Katsuki-chan is coming over to spend the night. Isn't that exciting?"

"Kacchan!" Izuku squealed with happiness. Katsuki was the little boy's best friend in the entire world. Of course, he would be excited for a sleepover!

Inko chuckles fondly. How could she ever consider babysitting a burden when having Katsuki over brought her own baby so much joy? Besides, they were way too young to present, so it’s not like she had anything to worry about. Plus, the Bakugou's were dear friends. She never minded helping them out.

"Kaccha Kaccha Kaccha," Izuku sang as he danced around the living room, swaying his hips and shaking his little fists in the air.

Inko was ready to pull out her camera when Izuku stopped with a gasp.

"What's wrong?" She started towards him.

"I need to get my toys ready!"

And with that, Izuku rushed off to his bedroom.

Inko couldn't contain her laughter. Her son was just too cute for this world.

Before she could catch her breath, a loud knock sounded at the door.

"Hello, hello," Inko greeted cheerfully as she opened the door. "Welcome!"

Mitsuki looked frazzled, her clothes rumpled and hair messy. It was very unusual for someone who was normally so well-kept. She let go of her son's hand and nudged him forward.

"Hey, Inko," she replied in a tired voice. "Sorry again, this is so last minute. Masaru's heat wasn't supposed to hit for another week."

Inko waved her hand dismissively. "Don't worry, I understand completely," she smiled kindly. "And little Katsuki-chan is always welcome here. Now go get back to your mate."

"Kacchan!" Izuku could be heard yelling in the background.

Katsuki ran towards the other boy, and the two began chattering away.

"Thank you, Inko. I owe you," Mitsuki bowed lightly and left.

The day passed smoothly, Inko doing chores and the children playing. They had their supper, and then it was time for a bath before bed.

Inko helped make sure both boys cleaned themselves thoroughly and then left them alone to soak in the tub.

Katsuki approached Izuku, close enough that they were nose to nose. Izuku had to cross his eyes to try to look back into his narrowed, red eyes.

"Dun like it."

"What?" Izuku was confused. Did Kacchan not like him anymore? Oh, no. That would be the worst.

"Your smell. I don't like it," he responded, pulling away slightly.

Now, Izuku was even more confused. "But I'm clean! I used soap and everything!"

"I know that, dummy!" Katsuki huffed. "But now you only smell like soap."

"Is that bad?" Izuku tilted his head to one side.

Suddenly, Katsuki was even closer. He held Izuku by the shoulders to keep him still, and he rubbed the side of his neck against the other's. The smell of their mixed scents slowly filled the small bathroom.

"There," Katsuki pulled back with a satisfied smirk. "Much better."

Izuku giggled. "Kacchan, you could've just asked to scent me."

If Izuku pointed out the slight pink tint of Katsuki's cheeks, Katsuki would blame it on the heat of the water.

Before long, Inko was back with two fluffy towels for the boys.

"If you two stay in there any longer, you'll turn into prunes!" She chuckled at the disgusted faces the boys made.

She tucked them into Izuku's bed and turned out the lights, shutting the bedroom door behind herself as she left.

The two boys waited a few minutes in silence, both knowing they should go to sleep but also knowing they wouldn't.

"Hey, Kacchan?" Izuku whispered.

"Yeah?"

"I really like your smell," he admitted shyly.

"Duh, I know that," Katsuki replied like it was the most obvious thing in the entire world. "I like yours too."

Izuku grinned brightly and hid his face in Katsuki’s chest. Katsuki slung an arm around the smaller boy and rubbed his face in his soft hair.

"Hey, Kacchan?" Izuku whispered again.

Katsuki hummed in response.

"My pee pee feels funny."

"Funny how?" Katsuki had felt… funny there before too, but he wasn't sure if his friend meant it in the same way.

"It's all hard and," he pushed his hips against Katsuki's thigh, "it feels good when it touches stuff."

Ahh. So it was what Katsuki was thinking.

"That happens all the time, 'Zuku," Katsuki explained. "When it does, you just gotta keep touching it 'til stuff comes out. Then it won't be hard anymore."

"Stuff will come out?" Izuku was confused. "Like pee?"

"No, stupid, it's not pee."

Now Izuku was even more confused. The only thing that ever came out of his was pee. "What is it then?"

"It's this stuff called cum. It’s really sticky, but it feels good."

“How do you know all that?” Izuku questioned.

“Because I know everything.”

"Of course. Kacchan is the best after all," Izuku reasoned, then put on his best brave face. “I think I wanna try it.”

"Okay, just do what I do," Katsuki instructed.

Katsuki turned so he was completely on his side, facing the other boy. He gripped Izuku's hips, pulling him closer so their little bodies were only separated by their underwear and pajama pants. 

Izuku was already feeling more excited by the closer contact. He wriggled his hips in an attempt to gain more friction. He thought he even felt Kacchan getting hard too!

“We can just keep doing this,” Katsuki explained, “but it’ll be better if we take our clothes off.”

“Why would we take our clothes off? We’re supposed to wear clothes unless we’re taking a bath and we already did that.”

“It feels better without clothes, and they’ll be dirty if cum gets on them.”

Izuku nodded firmly. Kacchan was so smart.

The two boys shimmied out of their clothes and laid back down.

Izuku gasped as Katsuki fit his small dick with Izuku’s smaller one and thrusted his hips up.

“Kacchan, do that again!”

“Shh,” Katsuki covered Izuku’s mouth with his hand. “I will, but you gotta keep quiet.”

Izuku sucked his lips into his mouth. He tried to focus on mirroring Katsuki’s motions and the foreign feeling building in his stomach.

Katsuki’s breathing stuttered, making it obvious that he was feeling the same.

“It’s… weird,” Izuku whined.

“That’s because you’re gonna cum,” Katsuki grit out through his teeth. “Don’t stop.”

“Kacchan,” Izuku called breathlessly. “I think… I’m cumming.”

He shuddered and keened as the thin, infertile liquid spurted out, getting all over himself and Katsuki.

“Ngh,” Katsuki groaned at the feeling of the wet warmth coating his own cock. “Me too.”

And Katsuki followed over the edge.

It took a moment for the two to catch their breath, but they both felt a sleepy satisfaction take over.

“‘Zuku,” Katsuki shook the other gently. “We can’t sleep yet. We have to clean up and put our clothes back on.”

“Mmm, don’t wanna,” Izuku nuzzled into Katsuki’s side.

Katsuki sighed in annoyance and stood up. He crept to the bathroom and grabbed the washcloth he had used earlier that evening, wetting it in the sink and returning to Izuku’s room.

“Cold,” Izuku whisper-yelled at the touch of the wet rag on his skin.

“It works better,” Katsuki explained. He finished wiping Izuku clean before cleaning himself.

Izuku grumbled and put his clothes back on, then curled up in the bed and pulled the blankets up to his neck.

Katsuki ignored the tight feeling he got in his chest as he watched the other.

“Hey, share some with me,” the blond pouted.

Warm and comfortable, the boys fell asleep quickly.

The next morning, Inko went to wake the boys for breakfast, but had to pause upon entering Izuku's room to take in the sight.

The two boys lay wrapped in each other's arms with their legs tangled. The blanket had been kicked to the end of the bed. Izuku was drooling into Katsuki's shirt, while Katsuki's face was buried in Izuku's hair.

Inko pulled out her phone and snapped a picture before creeping out of the room. She could give the boys just a few more minutes of peace. First, she had to share what she saw.

Inko: attachment image6368274.jpg

Inko: look how cute!!!

Mitsuki: omg look at our babies!

Mitsuki: future mates for sure

Inko smiled at the screen. She hoped they would love each other like that forever.

~

Middle school was challenging, to say the least.

At least in elementary school, no one else was interested in Izuku. Katsuki may not have been the nicest friend ever, but he always had a monopoly on the younger boy. Izuku was all his when he was bored or frustrated. He could always use Izuku in any way he pleased, no matter what and Izuku took any of his attention with a smile.

But in middle school things were more complicated. Kids were starting to present left and right, and their urges were becoming even stronger. Alphas and Omegas alike would touch themselves right in the middle of class as if they had no self control. Some even touched each other, all while lessons were going on. The teachers never stopped them as long as the lessons weren’t disrupted. Hell, sometimes the teachers touched themselves too.

Katsuki thought it was a waste of time to do that type of stuff during school, when students should be using their time studying, not fucking their brains out. He wouldn’t stoop that low, not even in times his dick ached to be touched.

Katsuki wasn’t the least bit surprised when he presented as an Alpha. It fit his personality perfectly. He was bigger and stronger than his classmates, too, which made it easy to deal with others, but it was still annoying.

Izuku was one of the last to present, but his petite frame and submissive nature- to Katsuki, at least- made him a popular target for other Alphas. When he finally did present as an Omega, the attention only got worse.

The biggest problem, however, was that Izuku was completely oblivious. He never noticed the advances made towards him, mistaking thinly veiled ill intent as genuine friendliness.

It infuriated Katsuki to no end.

The only silver lining was their opposing secondary genders. Katsuki didn’t care about other couples and their dynamics. Hell, he didn't think he cared about what Izuku presented as, but his instincts were pleased.

Katsuki pushed his instincts back as much as he could. He had plans, he didn't have time to think about useless things like mates. He was smart and strong and was going to do big things. He couldn't let another person hold him back.

In the back- the very back, pushed way, way down- Katsuki may have known he was being selfish. If he didn't want a mate, Izuku should be free to look for one, but that just felt wrong.

It wasn't like Izuku seemed to be looking. He tended to keep to himself, for the most part. He still followed Katsuki around like a lost puppy, but he was okay with that. They both were. For the time being, it was enough.

~

Izuku had always belonged to Katsuki. Everyone knew it. They may have just entered high school, but Katsuki made sure it was obvious to all the new faces they met. Katsuki's glare alone told them to stay far away.

It helped that the Omega always had Katsuki's scent on him. They hadn't exactly scented for quite some time, but they were always near each other.

From time to time, Katsuki would even give Izuku an article of his- worn- clothing. Not as courting gifts or anything, of course not. Just for practical reasons.

If Izuku was cold, he might as well take Katsuki's jacket. Never mind if someone else had already offered a jacket to him, even if they were closer and were already holding it out for Izuku. Katsuki didn't need to explain why he was suddenly behind Izuku, wrapping him in his own jacket. The others read him loud and clear. Izuku never said anything against it, so it didn't matter.

It also helped that Katsuki was always nearby. If he wasn't next to Izuku, he was surely lurking close by. It wasn't intentional. He just happened to need to be in the same room. And he wasn't staring. He just happened to turn his head in that direction. Pure coincidence.

Katsuki wouldn't let himself think about how he had turned into the lost puppy. He wouldn't let himself wonder if Izuku was ever truly the one following him.

One thing Katsuki definitely didn't do was follow Izuku to the bathroom. He had to take a piss! So what if Izuku was going too? So what if it happened every goddamn time? More coincidences. It had nothing to do with Katsuki being paranoid about how easy it would be for another Alpha to swoop in while Izuku was in a vulnerable position and take what was his- no, Katsuki was fine, he just had to piss.

Katsuki also wouldn't let himself feel dirty when he accidentally got a little piss on his hand and accidentally got it on Izuku as he brushed past on his way to the sinks to wash his hands. Why would he feel dirty about it? It was just another thing that happened from time to time. No meaning behind it.

The worst were the times when Izuku received confessions and courting proposals. While Katsuki was extremely surprised at how infrequently it happened, since Izuku was the epitome of Omegan perfection in his opinion, nothing else infuriated him more than the times it did happen. He was just relieved that Izuku had turned down every single one. Afterall, even if Izuku wasn’t his- at least, not officially- at least he didn’t belong to anyone else.

What Katsuki didn't know was that Izuku already had a mate picked out. Or that he shared many of the same possessive behaviors.

If Katsuki wasn’t around, Izuku would make up some lame excuse to find where he was and who he was with. If Izuku was near enough, he would throw death glares at anyone who had the audacity to take up Katsuki’s time, time he should be spending courting Izuku. Katsuki never noticed. Izuku could change his demeanor on a dime, whether it be sunshiney smiles towards Katsuki or minding his own business.

If he had something of the Alpha’s, either given to him or accidentally borrowed- definitely not stolen- he would scent it before returning it. Sometimes, he would even rub a bit of his slick on items. He knew it was wrong, but he just couldn’t help himself. Some primitive part of his brain told him that Katsuki needed his slick and he was a good Omega for giving it to him in any way that he could.

Their friends stopped saying anything. At first, teasing them about their obvious mutual pining was fun, but it got old after the boys denied it so many times. They were too cowardly to confess, too dense to notice the other’s feelings, and just plain stubborn. Everyone else could only hope that they ever got their shit together and ended the suffering they were not only inflicting on themselves, but everyone around them.

~

“Thanks again for going with me today, Kacchan,” Izuku smiled at the Alpha as they waited for the train back to school, fanning himself with his hand. “I really have no idea why no one else came!”

Katsuki scoffed, trying to act as if it was no big deal even when he was elated to have practically gone on a date with Izuku. “Either had shit to do or just don’t like superhero movies, I guess”

The Alpha didn’t need to know that no one else was even invited, and the ones who knew they were going were in on the plan.

“Their loss,” Izuku shrugged. “All Might movies are the best.”

“I’m just glad this one didn’t fuck up the original storyline,” Katsuki added.

“I can’t wait to get back to my room and turn on the fan,” Izuku sighed. He didn’t want their alone time to end, but he was starting to get uncomfortable. “It’s so hot out today.”

“It’s really not that warm out,” Katsuki noted, trying not to immediately show his concern. “And you’re usually the one who’s always cold.”

The train pulled into the station and Izuku led the way on board. It wasn’t too over-full, Izuku was relieved to find.

“But you’re in shorts and I’m in pants!” Izuku chuckled nervously, as they found a single empty seat.

“Sit down,” Katsuki gestured.

“Oh, I don’t want to sit if you have to stand,” Izuku waved his arms in front of himself.

“Fine,” Katsuki grumbled. “I’ll sit.”

“That’s fi-” Izuku’s response turned to a squeal as Katsuki pulled him to sit in his lap, arms wrapped around him to prevent any attempt at standing back up. “Kacchan?!”

Katsuki ignored the glances from the other passengers. “I’m not letting you stand. You look like you’re getting sick.”

“I-I’m not sick!” Izuku stammered. “I’m just hot.”

“You smell different too,” Katsuki narrowed his eyes.

“Different? How?”

Katsuki took a deep inhale, nose in Izuku’s curls. “Dunno… Sweeter, I guess.”

“Oh… Really?” Izuku tried not to shift too much in the blond’s lap.

“Yeah, like,” Katsuki took another sniff. “Deku?”

“Hm?”

“You’re not going into preheat, are you?” Katsuki sounded like the parent that caught their kid with a hand in the cookie jar.

“Wha- uh, no! Of course not!” Izuku tried to sound convincing. “I know better than to leave my room during preheat!”

“Not even for a brand new All Might movie?” Katsuki pushed.

Izuku was glad that Katsuki couldn’t see his face at the moment. He was close, though. Izuku definitely would leave his room during preheat to see a brand new All Might movie if it was just him and Kacchan.

“Um, well,” Izuku was losing his ability to focus on not fidgeting.

“You’re so fucking lucky I’m here to take care of your dumb ass,” Katsuki sighed, knocking his forehead into Izuku’s shoulder. “I’ll keep you safe ‘til you can get to your nest.”

Izuku’s heart squeezed in his chest at the Alpha’s words. He preened over how Katsuki took such good care of him.

“Fuck, you smell so good,” Katsuki’s said under his breath, unconsciously tightening his hold on the Omega.

“What was that?” Izuku sank back ever so slightly.

Katsuki found himself drawn towards the source of Izuku’s scent, rubbing his nose against the gland on Izuku’s neck, no longer able to find it in himself to hold back. “Smell so fucking good. Always smell so good, but fucking hell Deku.”

Izuku shuddered. “Kacchan… What are you doing?”

“Izuku,” Katsuki growled low in his throat. “You’re mine . You know that, right?”

Izuku’s breath hitched. He had to have misheard that. There was no way his feelings were returned. He didn’t want to ask, though, too afraid that Katsuki would take it back. Instead, he chose to be bold.

“I’ve always been yours,” Izuku turned as far as he could in the Alpha’s lap to face him.

Katsuki cupped Izuku’s freckled cheek, keeping him in place as he caught his lips in a searing kiss.

Izuku responded to the kiss with vigor. What he lacked in experience, he more than made up for in enthusiasm.

“Izuku,” Katsuki breathed, breaking the kiss. “My Omega.”

“My Alpha,” Izuku responded in kind. “Want you. Want you so bad.”

Izuku’s pheromones were getting stronger, his heat drawing nearer, encouraged by the willing Alpha. Many of the train’s other passengers were watching the couple intently, initially out of curiosity, but continuing due to lust. Katsuki and Izuku paid them no mind, completely lost within each other.

“Yeah? Want me to fuck your sweet pussy, baby?” Katsuki began unbuttoning the Omega’s pants.

“Please, Kacchan,” Izuku whined, writhing in the blond’s lap. “Need your cock.”

“You’re gonna fucking get it.” He ground his hips up into Izuku’s ass, making sure the Omega could feel how hard he was becoming. His other hand snaked underneath Izuku’s shirt to tease at perked nipples.

A moment later, Izuku pulled his hands away and stood up, pushing his pants and underwear down to his ankles and giving Katsuki a picture perfect view of his slick-shiny hole as he bent forward. Katsuki grabbed a smooth, freckle dusted ass cheek in each hand, squeezing and marveling at how they filled his large hands and how the excess squished out between his spread fingers.

"Already so fucking wet for me," Katsuki noted, licking his lips.

He had to force himself not to get distracted, instead tearing his hands away to push down his shorts. He got them to mid-thigh, just enough to give himself room. His hard cock stood proudly, precum beading at the tip and knot already beginning to swell at the base.

The Alpha grabbed Izuku by the hips and pulled him down on his cock in one smooth movement.

“Oh gods!” Izuku cried out.

Katsuki halted his movements, torn between wanting to bask in the tight, wet heat squeezing him and wanting to make sure his Omega was alright.

“Are you hurt?” Katsuki caressed his sides.

“No,” Izuku sucked in a deep, shuddery breath. “Good. Full. So full. ‘s big.”

“Yeah?” Katsuki goaded, no longer having to worry. “You like my big cock stretching open your cunt, baby?”

“Yesyesyes,” Izuku nodded rapidly.

“Like having all these extras watching while I take your virginity and make you mine?”

“Oh, yes,” Izuku’s little Omegan cocklet twitched as if preening under the attention. He wasn’t really paying attention to the surrounding passengers, but he knew all eyes were on them. “Want everyone to know I belong to Kacchan.”

“ Fuck yes,” Katsuki growled, grinding his cock deep in the smaller boy. “ Mine .”

Izuku carefully lifted himself up so just the tip of Katsuki’s dick was still enveloped in him, before dropping his weight back down, punching the air from his own lungs.

“Damn, ‘Zuku, slow down.” Katsuki gripped his hips tightly. “Don’t wanna pop my knot just yet.”

“But I want it,” Izuku pouted, desperately trying to move faster than the other would allow.

“You’ll get it, baby,” Katsuki crooned. “Let me take care of you.”

Katsuki lifted Izuku a few inches, before pulling him back down. He repeated the motion over and over, speeding up as he went. He moved the Omega effortlessly, as if he weighed nothing, just a ragdoll made to be fucked.

“Touch your pretty little cocklet for me,” Katsuki commanded.

Izuku obeyed, moaning in time with each thrust, punctuating each movement. It was as if the sounds were being fucked out of him completely out of his control. Lost in the pleasure, he paid no heed to his volume, letting his body react naturally.

Just as Izuku thought they had a steady rhythm going, Katsuki thrust his hips up to meet Izuku as he was pulled back down. The added force caused Katsuki’s cock to hit even deeper, hitting Izuku’s cervix with a pleasurable pain.

“Kacchan, I’m not gonna last,” Izuku whimpered.

“Wait, not like this,” Katsuki pushed Izuku up so he was almost standing. Izuku was about to protest, but Katsuki continued before he could. “Take your pants all the way off and face me. Wanna see your face when you cum.”

Izuku moved as fast as he could, almost falling over in his haste to pull his pants off over his shoes. He quickly scrambled over Katsuki, knees on either side of his hips, and braced his hands on the blond’s broad shoulders.

“Our stop is coming up soon,” Katsuki smirked as his cock was once again sheathed. “Better cum before we have to get off.”

“‘M so close,” Izuku answered.

“Me too, baby. Just a little more.”

Izuku leaned forward until their bodies were pressed flush together and claimed Katsuki's lips with his own once again. Despite being surrounded by strangers, Izuku only felt surrounded by the Alpha’s presence. His body felt electrified at every point of contact, his mind high on the knowledge that he was so desired, so needed by the one person he needed so badly. Before he could utter a thought, he was cumming, staining both of their shirts. His slick dripped over Katsuki's thighs, seeping into the seat beneath them.

Coaxed by Izuku's climax, Katsuki stuffed his cock as deep as he could inside Izuku, his knot catching and expanding, locking them together as he pumped his thick, hot cum into him.

"Bite me," Izuku pleaded as he was being filled.

"Not now baby," Katsuki soothed as best he could, already sensing the Omega's impending distress. "I will, I promise, but not here. Let's get you to your nest first."

Izuku sniffled, but didn't argue. He knew that he would be happier being claimed in the comfort of his nest over a dirty, crowded train, and he knew Katsuki would stay true to his word. No matter how much he wanted to be marked right that instant, he could wait.

Katsuki held Izuku tight to himself as they arrived at their stop, assuring they had all of their belongings before carefully standing. His knot wouldn't be going down for some time, so he would have to carry Izuku back to the dorms while they were still tied. He didn't mind, however, having a sense of pride at showing off that Izuku was his , even if he hadn't marked him yet.

“Hook your legs around me,” Katsuki instructed as he rose to his feet, holding Izuku by his thighs. He had to be careful not to pull on where they were tied, lest he risk hurting either of them.

Izuku complied easily, giving Katsuki a chance to remove one hand long enough to hike his shorts back up as high as they would go.

"Hope you enjoyed the show," Katsuki snickered behind himself as they exited the train, only catching a brief glimpse at the various states of dress of the other passengers, the positions of their bodies, and spilled bodily fluids.

Izuku blushed, more self-conscious now that he was sated, but not ashamed. He could never be ashamed of loving his Kacchan.

“Kacchan,” Izuku shifted, testing their tie as he was carried out of the station. “I think my heat’s about to start.”

Katsuki felt his cock twitch, unloading another spurt of cum inside the Omega, the thought of spending Izuku’s heat together stirring something primal inside of him. It took all of his strength to focus on the task at hand and not drag him into the nearest alleyway for another round.

“I know, baby,” he murmured. “We’re almost back to the dorms.”

It didn’t help that their progress was slowed by Katsuki’s shorts barely resting on his hips. He had to walk with a slight waddle to keep them from falling any lower. He considered just letting them fall off, which probably would have saved him time in the long run, but his brain wasn’t working at full capacity at the moment and told him not to stop moving.

Katsuki’s knot had hardly deflated when they made it back to the dorms. It wasn’t that he wanted to pull away from the now half asleep boy in his arms, but he knew that showing up like this would only cause their classmates to be extra annoying.

Surely enough, every face in the common area was turned on the new couple as they made their way inside. They were all various states of shock, but obviously happy for the two and glad that they had finally gotten their shit together.

“ Not a word ,” Katsuki hissed as quietly as he could, knowing full well that a commotion was about to break loose. “You can talk later, but he needs rest.”

“Looks like it,” a boy with half red, half white hair commented with a passive expression.

“Aww, such a protective Alpha!” A girl with short brown hair whisper-squealed, earning a hard glare.

“Hmm?” Izuku stirred slightly against Katsuki’s shoulder. “Oh, hi guys.”

“Midoriya-kun,” a stern-looking student with glasses spoke in what he thought was a soft voice. “Make sure to get proper sleep and stay hydrated.”

“I got him, Four-eyes,” Katsuki answered for the other, who just smiled sleepily, and headed for the elevator.

"Hey, 'Zuku," Katsuki called softly as they stepped onto the Omega's floor. "I need your key."

"Hmm," Izuku stirred. "Inmypants." His words slurred together, until he realized what the question implied. "My nest!"

Katsuki chuckled. "Yeah, your nest. Now hurry up, my arms are tired."

Izuku scrambled to get his room key out of the pocket of the pants crumpled in between their bodies. Now that he was fully awake, his impatience grew tenfold. The sooner he got to his nest, the sooner he could give in to his heat and finally claim Katsuki and be claimed in return.

Katsuki looked on fondly, thankful that his knot had at least gone down enough for all the pulling not to be too uncomfortable. In fact, it was starting to feel good. Very good.

Once Izuku finally pulled out the damned key, Katsuki snatched it from his hands. He fumbled a bit with the lock, finding the keyhole on the third try. As soon as they were inside, he kicked the door closed and locked it.

"I hope you're ready, because I won't be able to stop once we start," Katsuki's growl was as seductive as it was a warning.

"Kacchan, please," Izuku whined. "I'm so hot."

Katsuki lay the smaller down in his nest, not even pulling out completely as he hastily removed the remainder of their clothing. His own were easy enough, but he had no patience for Izuku's shirt, gripping the neckline and ripping it down the middle.

Izuku would have mourned the loss of one of his favorite shirts, but the display of his Alpha's strength was too hot for him to be upset.

"Take me now," Izuku pulled Katsuki down by the neck, kissing him hard enough for their teeth to clack against each other. He could feel himself producing enough slick for it to drip down onto the various soft fabrics beneath them.

Katsuki pulled away just Ling enough to murmer, "fuck, you're gonna kickstart my rut," before forcing his tongue past Izuku's lips.

Katsuki let his hands freely roam the smaller body underneath him as he rocked his hips. Now that he was allowed to touch, he vowed to himself to commit each curve to memory. The smooth skin felt finer than anything he had ever touched before. He thought about what it might look like stretched taut over a pregnant belly. He quickly pushed the thought away, though, not wanting to get too far ahead of himself.

"More," Izuku pleaded as he pulled away for air, their mouths still connected by a thin strand of saliva.

Katsuki complied, using his large hands to push Izuku's thighs up. He marveled at Izuku's flexibility, not receiving a single complaint about having his knees practically touching his shoulders. He would have to remember that for another time.

Izuku let out a high pitched cry as Katsuki snapped his hips harder. The new position had Katsuki's cock hitting impossibly deeper. The dripping slick causing the most sinful noises alongside their skin slapping together.

"How are you still so fucking tight?" Katsuki punctuated each word with a thrust.

"Cuz… you're … so… big…" The Omega wheezed.

"I'm gonna make sure this cunt never forgets the shape of my cock," Katsuki snarled. "No one else will ever be able to satisfy you."

"Don't want anyone else!" Tears spilled from lust blown eyes, spilling down chubby, freckled cheeks. "Never! Love you! Love you so much!"

Katsuki's breath hitched. He didn't expect to hear those words so soon, but he preened under them. He only found himself spurred on to fuck the Omega harder.

"I love you too, Izuku," Katsuki whispered with ardor, licking away the tears.

"Please, claim me," Izuku begged.

"Shh," Katsuki soothed. "I've got you. Gonna make you my mate, promise."

Losing cohearancy, Izuku's vocabulary devolved into a mess of yesses, pleas, and Kacchans. All he could do was rake his nails down Katsuki's broad back and take everything he had to give.

"Gonna cum, baby," Katsuki's rhythm began to falter. "Gonna stuff you so full and knot you, not let any of my cum go to waste."

"Yes, oh gods, yes," Izuku three his head back. "Fill me with your cum! Breed me!"

"Fuckfuckfuck," Katsuki continued snapping his hips until his knot caught, locking them together once again and filling Izuku with more cum. He simultaneously sank his sharp canines into Izuku's exposed scent gland.

Izuku managed to lock his own teeth in Katsuki's neck in return, savoring the taste as his tiny little dick squirted between them. The overwhelming mixture of sensations had his vision whiting out momentarily.

They both released their teeth, licking the wounds clean. Izuku couldn't help but feel as though everything had finally fallen into place, like things were suddenly how they were always meant to be.

Katsuki leaned back, easing Izuku's legs down to a more comfortable position and admiring the sight of his mate- his mate - coming down from his orgasm.

"Wait a minute," Katsuki squinted, looking just to the side of Izuku's head. "Is that my jacket?"

Izuku grinned sheepishly. "I may have one or two or several items of yours."

"You little shit," Katsuki gave a lopsided grin before planting a sweet kiss on his lips.

Izuku giggled into the kiss.

"Hey, Kacchan?" Izuku's emerald eyes met Katsuki's ruby ones.

"Hm?" Katsuki prompted him to continue, getting lost in their shared gaze.

"Can we change positions? You're kind of heavy."

"Wow," Katsuki snorted. "You really are a little shit."

Katsuki wedged his arms under Izuku, holding him tight, and flipped them over so that Izuku lay on top.

"Waaah-cchan!" Izuku squealed. "You could've warned me!"

Katsuki laughed at the Omega's adorable pout. He really was weak for his mate, wasn't he?

"I can't believe you're my mate," Izuku whispered once he had settled, as if their bond had given them some sort of telepathic link.

"Me neither."

"I really do love you," Izuku smiled into the blond's neck, right by his fresh claiming mark.

"I love you too, Izuku," Katsuki kissed the other’s head.

"Guess we kind of did this whole thing backwards, didn't we?"

"What's that supposed to mean?" Katsuki wrinkled his nose.

"We didn't court. We hardly even kissed before we had s-sex," Izuku stuttered, still a little flustered by the topic. "We only said we love each other right before officially mating-"

"Izuku," Katsuki cut him off with a hard glare. "Shut up. None of that stupid, socially constructed shit matters. You were always mine and I was always yours. If you really want me to court your ass, I'll do it now."

Izuku laughed. A real, genuine laugh. He suddenly felt so stupid. "You're right, Kacchan."

"Damn right I am."

Their banter continued as they waited for Katsuki's knot to go down, inevitably causing Izuku's heat and Katsuki's rut to signal the need for another round of sex.

"Shit," Katsuki huffed, seemingly out of nowhere.

"What's wrong?" Izuku asked, worried.

"I gotta piss," he sighed. "My knot's still too inflated to pull out."

Izuku could agree with that, still feeling the incredible stretch.

"Just go," Izuku tried not to sound embarrassed, requesting something so bold.

Katsuki sucked in a sharp breath, his cock twitching in interest at the idea.

"You sure?"

"Wanna be fully marked by you," Izuku said shyly.

Katsuki sighed. "Alright."

It took a few seconds for him to relax enough to let go, but once he did, Katsuki was in heaven. The combined warmth of Izuku's tight pussy and the mix of fresh cum and piss, plus the relief of no longer having to hold it was almost like another orgasm.

Speaking of which, as soon as Katsuki got over the initial euphoria, he noticed his mate squirming and moaning. Not only that, but his small cocklet was hard again.

“That good, baby?” Katsuki asked, still mid-stream.

“Feels so hot inside,” Izuku sighed, making shallow humping movements on top of Katsuki. “I’m so full.”

“Yeah? Well, I’m gonna keep you nice and full all the time. Make sure that pretty pussy’s always stuffed full of my cum or piss. Gonna get you a plug so you can keep it in even when you’re not on my knot.”

The remainder of the week continued in a similar manner. Any time Katsuki’s knot began to go down, they would be ready for another round. They tried every position they could think of, missionary, doggy-style, Izuku riding Katsuki, Katsuki fucking Izuku against the wall, etcetera. They hardly ever separated; only if absolutely necessary, like when Izuku’s body couldn’t hold any more liquid and he had to let it out before he could be filled again. Katsuki made sure they ate and drank water, thankful that Izuku had remembered to stock up before his heat, and at least get in a few naps. He may have been heavily influenced by rut-brain, but he still knew how to take care of his mate.

They were still reluctant to separate when their combined rut and heat finally ended. Classes were much less appealing than staying curled around each other in Izuku’s nest. But they could only afford to miss so many lessons, and Izuku’s sheets needed to be washed terribly.

Things were somewhat back to normal for about the next month and a half. Their parents were overjoyed with the news of their boys becoming mates and their friends were relieved that they would finally stop dancing around each other. Yes, things were normal, yet better.

For starters, Izuku and Katsuki were able to be much more open about their mutual possessiveness. Izuku just about always wore one of Katsuki's jackets, Katsuki had an arm around Izuku any chance he could get, and they proudly sported the marks on their necks.

Now, Katsuki didn't even need to leave the classroom if he had to pee. Even if he was in the middle of a conversation, he could just tell his mate, who would dutifully push his pants down and present himself for the Alpha to pull out the pretty little plug he now wore most of the time and replace it with his cock, putting the plug back in afterwards to make sure Izuku held it all in. Katsuki loved marking Izuku from the inside out, Izuku lived the warm and full feeling that only Katsuki could give him, and it was an explicit display of a sort of ownership. All around, a win-win.

Then Izuku started getting sick.

He swore he was fine, just a little nauseous sometimes, nothing to worry about. But, of course, Katsuki did worry. It started with Katsuki forcing Izuku to stay in bed, which made them both miserable since Katsuki wouldn't also be excused from class, but after a few days they both started to worry. That was when they made a special trip to the school nurse.

The little old woman listened to Izuku's symptoms and took his vitals. Seeing nothing immediately amiss, she asked a question that neither of the boys had been expecting.

"Is there any chance that you could be pregnant, dear?"

Izuku gasped and Katsuki choked on his spit.

"Well," Izuku considered the possibility. He knew in the back of his mind that the whole reason behind heats and ruts was biology’s way of encouraging procreation, but he never really considered it happening to himself.  "We did just mate during my last heat."

"And how long ago was that?"

"About six weeks ago," Izuku acted as if he hadn't been counting the days since he had been marked.

The nurse hummed. "And I'm assuming your heat triggered his rut?" She nodded her head towards Katsuki.

Both boys nodded.

"And did you use any sort of protection? Condoms? Birth control?"

"...no," Izuku blushed heavily while Katsuki avoided eye contact.

"Very well, then. Would you mind taking a test," she asked Izuku.

"Um, okay." Izuku was hesitant, but knew it was an important thing to do. Truthfully, he was afraid of what the test would say. He hadn't even considered that pregnancy was a very real possibility, but now he found himself wanting it. He didn't know what he would do if he took the test only for it to come back negative.

Katsuki squeezed Izuku's thigh in reassurance before he stood to take the test.

The next few minutes seemed agonizing as they awaited the result.

The timer Izuku had set on his phone finally went off, jolting him and his mate in surprise. Izuku wanted to run and check, but felt rooted to his seat.

"Come on, 'Zuku," Katsuki said softly, giving the Omega's hand a gentle squeeze. "Time to find out."

They slowly rose to their feet and took the few steps to the counter where the test sat.

Izuku blinked a few times to make sure he was seeing things correctly.

"Kacchan, is that…?" He trailed off.

"Yeah," Katsuki exhaled. "You're really…"

"I'm pregnant," Izuku whispered. He unconsciously moved a hand to rest over his belly, tears in his eyes and a wobbly smile on his face.

"You're pregnant," Katsuki repeated, taking Izuku's face in his hands. "With my pup."

Izuku let out a wet giggle before closing the gap between them, kissing Katsuki with force.

Katsuki couldn't fight the pride that swelled in his chest- didn't want to. Izuku, sweet, smart, beautiful, perfect Izuku, was not only his mate , but now he was pregnant, with Katsuki's pup .

Katsuki dipped Izuku back, deepening the kiss.

The nurse cleared her throat, breaking apart the celebration to get back to necessary matters. "Yes, very wonderful news. We will need to go over some information, make sure you are prepared, set up some appointments, and so on."

Izuku knew what she was saying was important, but he was having a hard time listening. All he could think about was how he was now carrying a tiny, growing life inside him. One that was equal parts himself and the person he loved more than anything in the world.

“I’ll take care of it,” Katsuki rolled his eyes fondly. He was beyond happy himself, but he had to be a responsible Alpha for his mate. “I don’t think he’s gonna be much help right now.”

The nurse chuckled in understanding. “Ah, yes. The joys of motherhood. You’re a good mate. Take care of him.”

“I will,” Katsuki attempted to will the burn away from his cheeks.

Pamphlets, appointment reminders, and vitamin recommendations in hand, the couple headed back to the dorms.

Izuku felt as if he was floating. He couldn’t take his hands off of his stomach. There wasn’t even a bump, yet, but he knew it would be there before he knew it. The other thing that seemed to be tethering him to the ground was Katsuki’s arm around his shoulders.

Katsuki couldn’t keep the small smile off of his face. He didn’t care about the questions or teasing that would inevitably come from their friends, he was too happy. Some part of his Alphan instincts told him that that was his way of fulfilling his life’s purpose, mating and having pups. He knew that there was more to life than that, but he sure wasn’t going to complain.

“Kacchan?” Izuku’s soft voice and big, round eyes pulled Katsuki from his thoughts. “How are we going to tell our parents?”

Shit. He hadn’t even begun to think about that.

“Guess we gotta do that, huh?”

Back at the dorms, they headed straight for Izuku's nest- Katsuki had taken to sleeping there ever since their mating- to discuss. They certainly didn’t need any of the extras being nosy and finding out about Izuku’s pregnancy before the child’s own grandparents. Oh gods, how would they react to being called grandparents?

“Let’s just text ‘em,” Katsuki shrugged. “Quick and easy.”

“Kacchan, we are not going to give them this kind of news over a text,” the Omega deadpanned. “Let’s take them to dinner or something.”

Katsuki groaned dramatically, but he was too weak towards his mate- his pregnant mate- to deny him. “Fine.”

“Thank you,” Izuku flashed him a sunny smile. “We can text them about that.”

Their parents agreed immediately, eager to see their boys under the pretense of homesickness.

When the day arrived, Izuku was nervous. The mixture of nerves and his ever present morning sickness made him miserable. If Katsuki hadn’t been there to comfort him, he knew he wouldn’t have been able to go.

“Izuku, sweetie, you look exhausted. Have you been getting enough sleep?” Inko worried over her son, holding his face between her hands and moving him around to inspect him.

“I’m okay, mom,” Izuku assured her. “We have some news, though.”

“What is it?” Masaru perked up with curiosity.

“I’m…” Izuku trailed off, not sure how to break the news. He looked to his mate for assistance.

“What do you think about Sobo-san and Sofu-san?” Katsuki smirked.

“What?” Mitsuki gasped.

“What do you mean?” Inko asked in a whisper.

“I’m pregnant,” Izuku finally said.

The table fell silent for a few seconds.

Then erupted into squeals of delight.

"Oh my goodness! That's wonderful news!" Inko was already crying.

"How far along are you?" Masaru asked.

"Let's get a round of sake for the adults!" Mitsuki cheered.

Izuku giggled as he relaxed his shoulders. He didn't know why he was so nervous in the first place.

"I'm so fullllll," Izuku whined as they made their way back to campus that evening, hand in hand. 

The surprise cause for celebration called for plenty of extra food and dessert.

"I look like I'm already in my third trimester!"

Katsuki laughed. "If you do, then so do I."

"It's called 'sympathy weight gain,' sweaty," Izuku teased. "Look it up."

"Oh, hell no," Katsuki shot back. "You may be eating for two now, but I'm not."

"Aww, you won't even eat a little extra for me?" Izuku batted his lashes.

"I'm not spending all my free time in the gym."

"Because you want to spend it with me, right?"

"You're such a dork," Katsuki scoffed.

"You didn't say no!" The Omega pointed out.

"Yeah, yeah. Don't get too cocky."

"You love me," Izuku grinned.

"I do," Katsuki squeezed Izuku's hand.

Katsuki wouldn't admit that he really did want to be by Izuku's side every second of every day, especially now that he was pregnant. And if he did admit it, he would blame it on his stupid Alpha brain.

Luckily for Katsuki, his stupid Alpha brain made dealing with Izuku's pregnancy symptoms much easier. Sure, he would grumble complaints from time to time, but there was nothing he wouldn't do for his mate.

Katsuki held Izuku's hair back when his morning sickness continued. He made special trips to pick up ice cream, mustard, pickles, cherries, and hot sauce (okay, that one he didn't mind) when Izuku started getting intense cravings. He weathered the mood swings, trying not to take anything to heart when Izuku got too upset. He was patient when Izuku's nest got bigger… and bigger… and bigger , helping him rearrange the entire thing when the Omega deemed it imperfect. He gave Izuku foot rubs and shoulder rubs when the extra weight of his belly made him sore.

Gods , how Katsuki loved that belly. He often found his hands wandering towards it without him noticing. Izuku's favorite, though, was when Katsuki spoke to it, telling their pup how loved they were, how he was going to spoil the shit out of them. Izuku often reminded Katsuki to watch his language, to which the Alpha would always argue that the baby wouldn't know what the words meant anyway.

He loved all of his mate's extra weight. The way Izuku got slightly softer and more curvy, the extra padding on his round ass, the swell of his perky little tits filling with milk, all around more grabbable. Being bigger, Izuku tended to prefer wearing Katsuki's clothes than maternity clothes- which the Alpha loved - at least until he got too big for those too.

Don't even get Katsuki started on how Izuku glowed . Katsuki never really believed that that was a thing that actually happened, but he was proven pleasantly wrong.

Possibly the best part of Izuku's pregnancy, though, was how he was always horny and needy. He wanted to be knotted constantly, sitting on Katsuki's lap throughout the entire school day, during lunch in the cafeteria, hanging out with classmates in the common area of the dorms, and any other chance he got. Katsuki was thankful for his heightened libido, only having a couple of times when his cock just needed a break. Luckily for him, Izuku was content with Katsuki's other methods of keeping him satisfied. Izuku loved having his pussy eaten out or his cocklet sucked. And Katsuki loved the taste of his slick and cum. Any time they had to be apart, Izuku needed to be plugged full of cum, and usually toyed with the plug or played with his cocklet.

But with the pregnancy progressing, both boys' possessiveness grew. Katsuki felt the need to mark his territory even when they were constantly together. At least once a day he would have Izuku on his knees, coating him with a golden shower. Of course, that typically ended up in a thorough fucking with Izuku on the floor, cheek pressed into the cooling puddle. Izuku even took to marking Katsuki. His favorite was when Katsuki laid on his back and he let go while riding his thick cock, letting the stream go everywhere as he bounced.

Izuku's pregnancy was just about perfect. Every check up held good news about both the pup's health and his own, and Katsuki was by his side at every one of them. Izuku cried tears of joy at every ultrasound. Katsuki didn't. He only had something in both his eyes every single time.

It wasn't until Izuku's water broke during class movie night that Katsuki panicked.

"Did you just piss?" He whispered Izuku's ear, the Omega curled in his lap.

"I don't think so?" Izuku whispered back, a little unsure.

"'Zuku," Katsuki took a deep breath. "Have you been having contractions?"

Izuku grimaced. "I thought I was having Braxton-Hicks. If we went to the hospital they would've sent me home since it's still a week from my due date and my water was still intact"

"How long have you been having them?" Katsuki tried to remain calm.

"Um, maybe a day? I think they started around lunchtime yesterday."

"And how far apart are they now?" The Alpha's patience was wearing thin.

"A few minutes? I haven't really been paying attention."

Katsuki sighed in exasperation, knocking his head against Izuku's shoulder. 

"Guys, it's time," Katsuki threw his head back and called out. "Someone get me some dry pants."

"At least we had a plan," Izuku chuckled nervously as their classmates scrambled in a semi-panic. "And I won't even have to be induced."

Amidst the chaos, the class managed to alert their homeroom teacher, call an ambulance, grab Izuku's hospital bag that had been packed in advance, and call the couple's parents.

The wait for the ambulance wasn't long, but everyone was on edge. Everyone except for Izuku.

"Deku-kun, how are you so calm?" One of the girls asked.

Izuku winced through another contraction 

"I'm ready for this baby to be out ," his smile looked somewhat threatening.

"Understandable," the girl backed away slowly.

Katsuki helped Izuku get into the ambulance, trying to control his urges to snap at anyone who dared to lay a hand on his precious mate. He knew they were only there to help, but he couldn't stop his instincts. He was relieved that they allowed him to ride with Izuku.

The contractions worsened in intensity during the short ride, causing Izuku to squeeze his mate's hand in a vice grip.

"Shit, Izuku, you don't need to break my hand," Katsuki teased.

" You did this to me, you should have to feel at least the tiniest fraction of the pain I do."

Katsuki snapped his jaw shut. He wouldn't make that mistake again.

Relief washed over them once they arrived at the hospital. Izuku was quickly taken to a room with a real bed. Unfortunately, Izuku couldn't get an epidural for several more hours since he wasn't technically in active labor, so Izuku continued to suffer and Katsuki said a silent prayer for the bones in his hand.

When he was finally given the epidural, both Izuku and Katsuki cheered. Seeing his mate resting much more comfortably was a weight off Katsuki's mind- and much needed relief for his hand.

Even with the epidural numbing the pain, the night dragged on. Inko, Mitsuki, and Masaru were allowed to visit, but no one could do anything but wait until Izuku was dilated enough to start pushing. 

"I'm hungry," Izuku pouted around 2 in the morning.

"I know, baby," Katsuki tried to soothe from his uncomfortable seat next to the hospital bed. "But you can't eat anything yet. Do you want some more ice chips?"

Izuku shook his head no, but still opened his mouth for Katsuki to feed them to him anyway.

They all tried to snooze as much as they could, but it was hard between the adrenaline, not being able to get comfortable, and the hospital staff flowing in and out of the room to monitor Izuku's progress.

The best news the couple thought they had ever heard- besides finding out that they were expecting, of course- was when the doctor said the Omega could start pushing. The parents were kicked out of the room until after the pup was born, but Katsuki was able to stay. He wouldn't have taken no for an answer if they tried.

Izuku had a hard time at first, since his body was numbed, but he kept getting told he was doing well. But the lack of pain didn't prevent the sheer exhaustion he felt. So many hours of labor, plus the added strain of pushing, was taking everything Izuku had in him.

"I can't do it anymore," Izuku cried at one point.

"Yes you can, 'Zuku," Katsuki carded one hand through his sweat soaked green curls and pressed a kiss to his forehead. "Just a little longer."

After a grueling total of 27 hours since his water broke, the pup made their appearance into the world.

It was a boy with a full head of green hair.

He cried from the moment he came out through being cleaned and measured, but settled down as soon as he was placed in his mother's arms.

Izuku and Katsuki could do nothing but stare in wonder. Even all pink and wrinkly, he was the most beautiful thing either had ever seen. When he opened his big, baby blue eyes, the pair only fell harder.

"Our baby," Izuku breathed.

"You did amazing, Izuku. I love you both more than you could ever know," Katsuki gently rubbed both of their heads.

"I think I know," Izuku smiled, "because I love you both the same."

"What color do you think his eyes will end up once the pigmentation develops?" Katsuki asked after a moment of silence.

"I hope they'll be red, like yours."

Katsuki snorted. "Of course you do. I just hope he ends up with your freckles."

The intimate atmosphere was soon broken by the couple's parents coming back in. They immediately began cooing over the baby, taking pictures, and asking to hold him.

"Like hell you're holding him now," Katsuki tried to keep his voice down. "I haven't even held him yet!"

Izuku wasn't ready to let anyone else have a turn yet, even his mate. No one could blame him, though.

Soon, a nurse came in to suggest Izuku try breastfeeding. They gladly used that as an excuse to kick their parents out once more. They were grateful that they were there, of course, but they wanted more time to themselves. They especially wanted to save some energy for when more visitors inevitably showed up.

"Do you have a name picked out?" A staff member asked for the birth certificate.

"Bakugou Akio," Izuku answered confidently, not taking his eyes off of him. "Because of the brightness he brings to our lives."

Katsuki was glad that was the name they had settled on. It seemed to suit the tiny pup perfectly.

With that, they were left alone again.

"Do you think I'll be an okay dad?" Katsuki asked, a hint of nerves in his voice.

"You'll be a great dad," Izuku smiled softly. There wasn't a shred of doubt in his mind. "After all, Kacchan is the best."