Archive of Our Own

It had been years since they defeated Muzan, and the Demon Slayer Corps had no more demons to kill, and Inosuke was throwing up behind a boulder. His hands were reduced to bloodied callouses by his swords, wiping them on his hips. They never got used to the wear in the way that Tanjiro’s did, tearing and bleeding and coming back together just long enough for him to shred them apart again. He’d never seen them fully healed and he didn’t want to, like that would mean letting go of his rage. No one else was still angry in the way that he was, didn’t have the fire he did still smoldering a hole through the center of his chest, right at the crosshairs of his scar from his fight with Douma. At first, he’d assumed that Sanemi would be that person, but before he knew it the guy was a completely different person, one who told people he loved them and treated Nezuko like a little sister, worlds apart from when he’d literally tried to kill her. So with Sanemi all switched up on him, and even Giyuu’s silent, seething, ocean-thunderstorm rage turning to peaceful, enduring spring waterfalls, Inosuke was left alone in his persistent anger.

Inosuke kicked every tree root and loose rock he could reach along his path, growling and hissing at any animal dumb enough to end up in his general vicinity. He continued to spit the sour taste out of his mouth, lifting his boar mask to target plants growing on the path. It hadn’t been nearly long enough when he returned to the Demon Slayer Corps Headquarters, and they still called it that despite the name no longer having any relevance, because how were they supposed to just leave after everything that had happened?

Inosuke entered the clearing to see Tengen Uzui standing up against the wall with a cup of water in his hands. He had a tendency to just appear places, usually with one or more of his wives, but at the moment he was alone. His presence was brief but constant, and him and Inosuke had developed a comfortable friendship over the years. Tengen might not still have the anger, but he definitely understood it, even as he was smiling and drinking and laughing at whatever story Tanjiro and Zenitsu were telling him about Inosuke’s uncontrollable rage. 

“Hey, can I have that?” Inosuke asked, skipping both steps to jump up next to Tengen. 

“My… water?” Tengen questioned. He paused for a long moment, biting his lip and cursing under his breath. “Sure, whatever.”

Inosuke took it, lifting his mask off his head as he swished the first gulp around in his mouth, spitting it between their feet as Tengen stared on in disgust. He drank down the rest of it in another long chug, doubled over and wiping his chin. 

“Are you okay ?” Tengen asked, taking back the empty cup Inosuke held out. 

“‘Course I’m not.” Inosuke scoffed. Tengen, to his credit, laughed along with him, but when he looked up his gaze on his exposed face left Inosuke feeling warm. There was an affection in it, and the rich smell of velvet and sage and cedar washing over from where the alpha towered above him. 

“Training go well, at least?” Tengen added, reaching out and patting the top of Inosuke’s head somewhat hesitantly when he gave a thumbs-up. He felt himself leaning into the touch, warm and comfortable. Tengen smelled good, but part of Inosuke always thought that. “We can go over some sword skills another day if you want.” 

Inosuke nodded, pleased by the offer. Tengen was pretty much the only person who still humored Inosuke’s antics after so many years. Even Tanjiro and Zenitsu had stopped training with him, grown up and moved on enough to end the useless regimens. He wasn’t sure why the man did it, but he never questioned it for fear of him stopping. He’d give Inosuke pointers for dual wielding, yell at him while he ran laps or help him stretch his already elastic joints to their limits. 

He’d even taught Inosuke to shoot a bow and arrow, Tengen using his own modified contraption that he held and released from his mouth to accommodate for his hand. Tengen had picked it up during his Shinobi days, and Inosuke had hit a bird or two in his lifetime, but neither had ever gotten particularly skilled in a weapon that had always been ineffective against demons. Now, they’d spend hours in peaceful silence, shooting and collecting volleys of arrows one after another, not for anything but themselves. Never once did Tengen ask Inosuke what he was gearing up to fight with that bow, just accepting his need to continue. He enjoyed it in his own right, coming to find Inosuke eating with Tanjiro and Zenitsu with both their bows in his hand and two quivers slung over his shoulder and getting just as excited as Inosuke when they both had a particularly flashy round. 

Inosuke thought about the first time he’d felt that draw of attraction to Tengen, watching his hand knock an arrow swiftly and single-handedly. His aim wasn’t rushed, but he also didn’t take a second longer than he needed to, drawing with the strap around his wrist and clenching his teeth to trigger the release. Anyone else probably would’ve looked stupid doing it, but Tengen had an effortless coolness about him. It hit inside the circle of the bullseye, joining a nice little group centered around the first two rings. 

Inosuke tried after him, knocking the arrow and yanking the string back, stretching his shoulders. He breathed in, centering his aim and letting go on his exhale like Tengen taught him. It landed near the center, but still outside the bullseye, joining his group skewed low and to the right. 

“Steady, pretty boy,” Tengen’s frame encircled him, tightening his stance as Inosuke knocked another arrow. “This is a game of precision and patience, two things the both of us could always do with more of. You still want to throw your arm, move your head and watch the kill. But when you release, the only things that need to move are the first knuckles of these three fingers.”

Tengen’s fleeting touch on his fingertips made him gasp involuntarily, and he half-covered the sound with an awkward grunt. 

“Nothing else, so put all your control right into here, make everything else part of the scenery. Feel for the right moment to let go, I know you’re able.”

“Your strength is in your senses, not your muscles.” Inosuke mumbled. 

“That was… surprisingly wise.” Tengen observed. 

“Genya told me that,” Inosuke said quietly, remembering them out here, shooting at scrapped tin from tuna cans, finally teaching Inosuke after weeks of pestering. Genya might’ve died eating demons and wielding a sawed-off shotgun, but he was a sharpshooter at heart, laying in the grass propped up against a rifle, judging the wind with his hair and pinging metal over and over like a machine. 

There were a few guns in the armory, relics of the former slayer. Sanemi didn’t touch them, so neither would anyone else. But Inosuke had thought more than once about pulling them out during one of these afternoons with Tengen, getting to be the one teaching the old man something for once. The way Tengen’s hand would look wrapped around the small revolver sitting in there, his eye narrowed in focus and determination. How many times Inosuke would get to watch him try, cursing under his breath before he finally got the hang of it. He wondered if Genya would be bothered by him taking out his rifle again when there was no one else who could compare with his skill. Maybe he’d just tease him a little and let it go. Maybe he’d be happy to see his prized possessions getting some use again. 

“He was right, and it’s especially true advice for you. I know you can use your senses to your advantage. Why try to look where the arrow’s going when you already know ?”

Inosuke nodded in understanding. He hadn’t thought about it that way before, but now he centered his weight, stilling every inch of his body, feeling the light breeze coming in from the east, the flock of birds flying overhead, the presence of the others gathered in the building behind them, the cloud drifting to shade their little patch of grass. It took longer than usual for him to feel ready, but when he finally let go, all that moved were the tips of his pointer, middle and ring fingers snapping open, his eyes shutting when the arrow left his control. When he opened them, he saw what he already knew to be true: a perfect bullseye. 

“Flamboyant work, boar boy,” Tengen clapped him on the back. “You’re not allowed to get better than me, hope you know that.”

“Already am.” Inosuke had shot back, sticking his tongue out. 

“Good one,” Tengen chuckled, throwing his bow on the rack and starting towards his target to collect his arrows. “I’d make you add up our scores if I thought you could count into double digits.”

…

“Welp, let me know if there’s anything I can do to help.” Tengen said, snapping Inosuke out of his trance as he adjusted the eyepatch on his face. The shine of the massive gems in the sun reflected against his polished nails, a casual motion that Inosuke suddenly found himself taken by. Tengen was always hot, Inosuke wasn’t blind , but that had only recently felt like a truth that had any importance to him specifically. 

“Inosuke! Hi!” Tanjiro smiled warmly. “Are you trying to get back to your place?”

“I dunno,” Inosuke grunted. He could smell Tanjiro from here, and yeah he did usually have the scent of burnt stuff on him, but Inosuke enjoyed it, ignited flames and charcoal and firewood. On instinct, he moved to press his wrist to Tanjiro’s, something the other boy usually allowed him to do. There wasn’t anything sexual or even romantic about scenting Tanjiro, just a comforting feeling from the force of habit that had endured for nearly a decade now. Together, their scents reminded him of a bonfire put out by the rain, and the smell made him feel at home. 

“Sorry, you uh, can’t do that right now. I’m already not having the easiest time.” Inosuke then noticed the flush on Tanjiro’s tan cheeks, the way his eyes were darting up and down Inosuke’s shirtless frame. 

“ Goddamnit .” Inosuke groaned. “Am I—?”

“Yeah…” Tanjiro chuckled uncomfortably, scratching the back of his neck. “ Sorry . It’s not bad, I’m just already a little lightheaded. You didn’t pass any alphas on your way in, did you?”

He thought back to the way Tengen had looked at him. Of course it was just his heat. But what had he meant then, by helping ? He banished the hopeful thoughts from his mind. 

“Nah, just you.” Inosuke lied. Unlike Tanjiro, he actually knew how to do that. 

He left the headquarters building out the back and set out along a small hilly path dotted with residences. Pretty much everyone that was left had a little place here, and he rushed past the other’s places, hoping no one was inside. His own room was a bit further up the path, mostly so people didn’t have to hear his intermittent screaming and he could have easy access to the forest, but for these situations as well. Inosuke knew he tended to have a certain… effect on other people when he was in heat. He’d grown up with no reason to bother controlling these sorts of things, and when he presented as an omega he still didn’t see the point in doing anything to mitigate his scent or his heat. He wasn’t the type to have shame over his omega-ness just because some people might think he should. But at least according to Tanjiro, who was usually his guide for these things as a beta with a wildly good sense of smell, and the alphas he’s gotten to talking to, there’s something about him that’s particularly tempting, especially when he’s going into heat. They didn’t understand it, he didn’t understand it, and he had no choice but to deal with the occasionally uncomfortable exchanges he had with people because of it. 

He passed Aoi, biting the inside of his cheek the entire time. Of course he was going to have to walk by another alpha on his way here. At least if he had to pick someone, it would probably be her, a slender, slightly uncharacteristic alpha who stood an inch or two above him, smelling like fresh laundry and clean soap and lemon trees, like the sunrise on the first day of a new season. 

“Call if you need me.” Was all Aoi said as she walked by, obviously stifling her reaction to him with a wrinkled nose. He knew from experience that she would come bring him food or water or clean towels at the expense of her own sanity, because Aoi did nothing if not take her responsibilities seriously. He also knew that she’d come inside his room and fuck his brains out if he begged her, as they had an enjoyable time doing that during a couple past heats. Inosuke considered asking her now, but she looked busy and like she was trying to ignore him to the best of her ability. He couldn’t help but feel like he was a box to be checked with her, spending a heat with him the same way she’d set his broken leg, which wasn’t necessarily a bad thing, just a fact. If he asked for it she’d probably give it to him, but more because he wanted it than because she did. 

Even if Aoi was pretty and strong and willing to sleep with him every once in a while, his mind kept turning back to Tengen. He wanted to know how that masculine, all- enveloping scent of his would smell right on the skin of his neck, or better yet mixed with his own. It was still on his mind when he opened the door to his room, a dim, disorganized little place that he was still happy to consider home. 

He began to notice the patterns of his own body once he was alone in his space, the growing slickness between his legs accompanied by a dull ache, and the feverish quality infecting his skin. Perhaps embarrassingly, he always had a nest in the center of his room, another urge he didn’t bother trying to suppress. It was perfectly fine for normal nights, but now it wasn’t nearly enough, not even after throwing everything else he had in the room at it. 

The issue wasn’t the feeling , he realized as he sat inside it, but the smell . Everything just smelled like him, which wasn’t even a scent his own nose could pick out. He considered going into Tanjiro’s place and stealing something, not like he would care, or from Zenitsu, who would care but get over it eventually, he could even find Aoi again and ask her. Inosuke flopped onto his back, sliding a hand between his legs that did exactly nothing to satisfy the aching down there, which was turning the corner from irritating to painful as he fumed angrily about how much this heat was going to fucking suck. 

His brain was starting to tie itself into knots in hormonal desperation and loneliness when he heard a soft knock at his door. 

“I just wanted to come check on you, after earlier,” The smell of velvet and burnt sage and mint leaves was a necessary interruption, and he drank it in happily, watching Tengen’s form fill the entryway. Inosuke was still touching himself absently, unphased by Tengen’s presence. It’s not like he didn’t know what he was doing in here, no point in hiding it. There was no indication Tengen minded as he set down a cup and pitcher on the floor, avoiding actually stepping into the room without permission. “Brought you some water, too.”

“Am I torturing you right now?” Inosuke asked. He could see the way Tengen’s usual consistent composure was slipping, the hand he ran over his forehead, sweat dripping to his pale, sparse brow and the little frustrated noise that escaped his lips.

“Two of my wives are omegas, so I’ve got a better resistance than most,” Tengen answered. “But this is still—“ He sucked in a deep breath. “a lot .” 

“Hmph.” Inosuke snorted unhappily. Of course he’d forgotten about the wives. Fuck him for that. 

“I mean… they don’t care what I do with other people.” Tengen replied, leaning against the narrow doorframe, regaining some of his usual confident image. 

“You sure?” Inosuke asked, holding back a whine when his knuckles brushed his clit. 

“Are you ?” Tengen shot back. “Don’t worry about whether I can think for myself, I’m not the one in heat right now.”

“Shut up, old man.” Inosuke spit. “I know exactly what I’m doing, ‘course I want you.”

“Is that so?” Tengen smirked with easy satisfaction.

Inosuke looked up at the broad, tall alpha watching him, his eyes no longer polite enough to be looking anywhere except the wrist buried under his waistband. He imagined that wide, frankly idiotically massive hand inside of him instead of his own stupid little sausage fingers and pedaled his legs in frustration. 

“I’m not even there yet, just trying to be.” Inosuke complained. “This heat is going to last me two weeks at this rate. No duh I want your help, plus you’re you .”

That was enough to convince Tengen to take a single step into the room, his scent following. “May I?” 

Inosuke hopped out of his nest, jumping in front of Tengen and ignoring the dripping, wet heat of his core to tug at the sleeve of Tengen’s yukata. 

“At least gimme this,” Inosuke insisted, his other hand pulling at the robe's tie until it was falling open. “Smells good.” 

Tengen didn’t protest, just let Inosuke expose his naked body, the sight of which shocked him into silence for a long moment. The thought of Tengen’s cock had crossed his mind, at the very least as a kind of thought experiment for what a man of his stature would look like down there. But whatever he’d speculated about couldn’t compare to the long, thick cock sitting heavily between his legs, just beginning to swell with attention. If he didn’t still have his pants on, Inosuke would be dripping onto the floor. 

“Oh, you poor thing,” Tengen cooed, unbothered by Inosuke exposing him. “I feel so bad that an omega as perfect as you doesn’t have anyone to enjoy this with.”

“Yeah, it’s never fun .” Inosuke mumbled. 

He leaned down and pulled a cool, wet cloth from the tray, wiping it along the dark red blood streaked on Inosuke’s sides from where he’d wiped his bloody palms earlier, slowly cleaning his torso and cooling him down a little, though he was so hot it felt like the water was evaporating directly off his skin. 

“Hands?” Tengen requested. 

Inosuke shoved them behind his back, silently shaking his head. Something was humiliating about letting Tengen see them, a childish display of self-destructiveness.

“ Please ?” Tengen asked. “For me?” 

“Fuck you,” Inosuke grunted, but he still turned his palms up in front of Tengen. 

“You do look sort of pretty covered in blood,” Tengen mused. Inosuke didn’t wince, not even when the fabric scraped against his raw skin, but Tengen still looked to him with worry in his darkened eyes. He grabbed a roll of bandages off a low table and gently wrapped each hand. “Wouldn’t change you for the world, but I do wish you could gain some self-preservation instincts, maybe settle down a little.”

“Not my thing,” Inosuke answered. 

“You’ll never settle down, really?” Tengen asked, reaching out and placing his hand around the back of Inosuke’s head, easily holding the whole thing in his palm. Inosuke’s scent came off him in waves, petrichor and wet earth and greenery and the sweetness of his building arousal, Tengen rumbling low in his throat as he twisted his hand around to rub his wrist to Inosuke’s neck. “Not even if the right person asked you to? Someone who could make this fun ?”

Why in the fuck did Tengen sound so hopeful ? Since when did he scent Inosuke’s neck and then close his eyes and smile like it was the best thing he’d ever experienced?

“What, you’d be the right person?” Inosuke asked, crass and blunt as ever. 

“Well that much goes without saying, you can’t possibly be questioning whether or not I would treat you right,” Tengen smiled, full of his usual performative confidence. “And I have no doubt that you’d make a perfect fourth wife.”

That was a particularly good line, one that ignited that primal part of him and made him feel weak in the knees. The idea of being one of Tengen’s pretty wives, latched onto his arm, scenting his neck in public, and never spending a heat alone again spoke to all his raging hormones. 

“Need you.” Inosuke grunted, snatching Tengen’s wrist in his and dragging him to his nest, no care for how desperate and demanding he might sound. 

Tengen let his yukata fall off his shoulders, Inosuke admiring the long lines of his back as he tore it off and took a long, deep breath of Tengen’s scent on it before adding it into his nest. His senses were filled with it, and this was perfect, so perfect, exactly what he wanted and needed so badly, and when he threw himself down Tengen followed without hesitation.

“Good?” Tengen asked, reaching his hand out for Inosuke’s tousled hair again. When he nodded in approval, Tengen dragged Inosuke into his lap, wrapping his arms around him. “This is very comfortable.”

“You like it?” Inosuke asked, readily seeking praise for his nest. 

“Mhm, I do enjoy a good nest as much as the next guy,” Tengen laughed, settling himself in the space, turning his head to bury his face in it, foot bumping where Inosuke’s mask was carefully tucked into a corner. “Fuck, you smell amazing. And you’re shockingly lucid right now.” 

“Powers of the Beast Hashira,” Inosuke smiled, sliding his back into Tengen’s chest. Obviously he was the Beast Hashira even when there wasn’t an active Corps, and no one other than Zenitsu even bothered to try denying him the title. 

“I don’t think it’ll last, though,” Tengen mused. “I’m curious to see what you’re like when you really want me.” 

“I always want you, stupid fuck,” Inosuke reached back, flicking Tengen in the forehead. 

“ Oh ?” Tengen asked, sounding genuinely surprised.

“You look really good shooting your bow.” Inosuke admitted gruffly. 

“As do you,” Tengen replied, his hand reaching down towards the fur over Inosuke’s hips, carefully unlatching it and letting it fall away. “I’ve thought so for some time now. Took me long enough, to finally see how pretty you really are.” 

Tengen’s hand slid downwards, covering Inosuke’s with his palm. He gasped, pressing his hot skin against Tengen’s front, feeling how the heat grew on their bare skin. Inosuke keened happily with the added pressure, falling into the overwhelmingly good feeling easily. 

“Like shooting an arrow,” Tengen whispered in his ear. “Just the tips of your fingers.”

Inosuke listened to his direction instinctively, slowing his fingers into languid circles. He was reminded of why he had learned to trust Tengen when he felt his square fingertips padding at his entrance. 

“Fucking hell,” Tengen cursed as his middle finger slipped easily between Inosuke’s slick folds and into his entrance. “You are so wet, I don’t even need to try.”

“More,” Inosuke demanded, clamoring further up Tengen’s body to enhance his angle, grinding his hips down greedily. 

Thankfully, Tengen granted his wish without protest, sliding the rest of his finger in to its base. Inosuke gasped, shuddering in Tengen’s hold. The musky smell of his arousal began to fill the small room, so intense that Tengen could feel it in his lungs, making his blood race. Inosuke was sitting and purring in his arms, somehow even more than he could’ve imagined. That assumption was stupid from the beginning, to ever think Inosuke wasn’t going to give anything he did ten times more than anyone else, this included. 

“Fuck, Uzui-san—“ Inosuke whined. 

“Call me Tengen, gorgeous.” He nipped his teeth on Inosuke’s ear, his head thrown backwards in bliss. “Though I’m very impressed you got my name right.” 

Tengen pressed another finger into Inosuke, out and back in with a smooth glide of his wrist, crooking his two fingers along his walls, his whole body curling up in pleasure. The part of him that wanted to talk about this odd, wonderful thing finally manifesting between the two of them was quickly and effectively being silenced by the one that knew he wasn’t going to be able to resist Inosuke’s mind-numbing body literally dumped into his lap. 

“There you go, Inosuke-sama,” Tengen praised, his voice low and rumbling in his throat. “Just wanna make you feel good.”

That was. Really weird. But Tengen was also weird like that, maybe? He always said whatever the fuck he wanted, and that’s just how it was. So Inosuke accepted the term readily, the way Tengen was talking to him lighting every nerve on fire. 

“Don’t be too shocked, boar boy, I know where I stand,” Tengen said, listening to his stuttering heartbeat. “I was never half the slayer you ended up being, you know that, don’t you? What you did is in an entirely different league.”

Inosuke shook his head. What he and Tengen had done as demon slayers couldn’t be compared, and not once did Inosuke ever genuinely think he could match up to the Sound Hashira who saved his group as kids. 

“You knew when to walk away,” Inosuke replied instead. He’d thought it was stupid at the time, but he’s gotten older and marginally wiser, learning to respect Tengen for it. “I still can’t.”

Tengen was a bit lost for words on that one. “You’re trying.”

“I have no clue what the fuck I am.” Inosuke said back, grabbing Tengen’s left arm and sinking his teeth into the scent gland there with frustrated vigor. 

The shock of it, pain and pleasure and overwhelm almost made Tengen scream , stifling it on the curve of Inosuke’s muscular shoulder until he was drawing blood. “You unbelievable little slut . This conversation isn’t over.” He slurred the words, but it still seemed like Inosuke got them. 

“It is, because I’m right.” Inosuke said, sounding muffled and underwater to a still-overwhelmed Tengen. 

“Not true.” Tengen felt like he could hardly talk in the haze of Inosuke’s scent, musk and warmth and bark and dewdrops, dizzy and drunk on him. “You’re you , I would know, we spend most of our time together nowadays. I see you when you’re about to shoot a bullseye, or playing in the mud with the kids or still picking your swords up after all this time.”

“I should be able to put them down .” Inosuke grunted.

“You carry them so the rest of us don’t forget.” Tengen said softly, a truth he always knew but never voiced. They wanted Inosuke to be happy above all, but seeing his persistence reminded them of the feeling that had defined their lives, the lives of all their lost friends. But coming to terms with things didn’t have to mean changing. No one wanted that from him, least of all Tengen.

“Stop making me feel warm and fuzzy,” Inosuke growled back. “I let you in here to fuck. Mushy stuff later.”

“Very well,” Tengen replied, doubling his two fingers inside to four in one breath, Inosuke making a noise somewhere between a purr and a hiss as he adjusted to the sudden additions. 

Inosuke’s hands pawed at his own pants with an unusual lack of coordination, wanting them off but too worked up to move properly. 

“ Can’t ,” Inosuke moaned desperately, grinding his body down into his nest. 

“Easy, I got you,” Tengen said, pulling the pants down and letting Inosuke violently kick them off, flinching at the way he writhed and screeched at the emptiness when Tengen removed his hand from inside him to do it. He’d seen Inosuke at death’s door, and it was nothing compared to the pain he seemed to be experiencing in this moment.

Inosuke breathed a sigh of relief when Tengen replaced his fingers, curling them all in as deep as he could reach, his angle enhanced with Inosuke’s nudity. He stopped to enjoy the wild, midnight blue hair centered around Inosuke’s soft, wet cunt and spreading up to his belly button and down onto his thighs. It looked dark and shiny against the weathered skin on the back of his hand, and he couldn’t resist folding Inosuke in half against him and fucking as much of that hand as he could fit inside, feeling Inosuke bite at his bicep in retaliation as he vibrated in his grip.

“ More ,” Inosuke begged, even as his whole body bounced against Tengen’s hand. “It hurts so bad .”

“I don’t think I could manage to fit any more of my hand in here,” Tengen said, Inosuke groaning in frustration. The next logical step from here would probably be tucking in the thumb he has crooked around Inosuke’s entrance and fisting him. 

“Just fuck me,” Inosuke whined, trying to find purchase on Tengen’s sweat-sheened body behind him. “I need it inside me, please Tengen.” 

He held back the possessive growl building in his throat at the way Inosuke said his name, pulling his wet hand out of Inosuke to another chorus of moans and screams. Before he could fully register the pain, Tengen was flipping their bodies around, his left arm pinned across Inosuke’s chest to hold him down. He pressed his cock against Inosuke’s slick folds, covering himself in warmth and lubrication, his hand reaching out to trace the lines of Inosuke’s scar. 

“ Still .” Tengen said, not really meaning to command it but doing so anyway, Inosuke freezing completely under his grip. He didn’t fight it in the slightest, almost appreciating the relief it gave him from his uncontrollable muscles.

Inosuke’s eyes were welling with fat tears, spilling down the sides of his face, whimpering with the bouts of painful need wracking his body with nowhere to dispose of his energy. Tengen couldn’t stand to see him like this any longer, strung out to a torturous degree when he deserved all the pleasure in the world. He finally pushed his hips upwards to bury himself inside Inosuke, sliding in most of his shaft easily, Inosuke moaning and sobbing in relief. 

“ Finally .” Inosuke’s voice cracked out, shaking with each thrust into him. 

“Good boy,” Tengen praised, fucking into him with a consistent, unrelenting rhythm. “Do you feel better now that you’re filled with my cock?” 

Inosuke wiggled his hips happily at the compliment, nodding his head. “Being empty hurts so bad , you have no idea.” 

“I’m gonna make sure you never feel that way again,” Tengen promised, stroking the back of his hand down Inosuke’s face and watching him jerk in reaction to the touch. His face was so deliciously sensitive, a fleeting touch against it enough to make his whole body react.

When Tengen actually knotted him, he watched Inosuke orgasm like it was the last thing he was ever going to do, a short, shivering buildup to a drawn out display of his jerky muscles clinging to anything he could reach to ground him. He screamed and cried and hit Tengen’s shoulder with his balled fist, but Tengen also knew this beating was nothing compared to the one he’d get if he pulled out now. 

“Come on baby, just breathe and adjust,” Tengen encouraged to Inosuke’s feral, mindless eyes. “You’re such a perfect omega, so tight for me, taking my knot so well.”

Inosuke whimpered at the praise, his chest finally settling with deep breaths, body adjusted to Tengen’s presence inside him. As soon as Inosuke got used to the feeling he was shifting and sliding, seeking more stimulation. The warm pressure on his knot felt like someone squeezing the air out of his lungs, vision blurring on the edges. He could only see the dim outline of Inosuke below him, grinding on him until he’s shuddering his way through two consecutive orgasms. 

As soon as Tengen could breathe again he was pressing himself up into Inosuke’s full, oversensitive cunt. At first, Inosuke was writhing and struggling through it before going completely limp for a moment, eyes blank and mouth open and drooling, not a single thought in his mind. When Tengen came inside him he spasmed with it, his blissed out face buried in his nest. 

…

Inosuke had been holding onto his knot for hours by now, waning in and out of consciousness, mumbling gibberish and grinding his soft, solid hips down on Tengen’s body. He couldn’t recall how many times either of them had orgasmed, Inosuke hardly able to go ten minutes without one and his own body completely out of his control once he’d knotted Inosuke. It had been enough to leave Inosuke a little bloated with it, the lowest curve of his muscular stomach bowed out where Tengen had filled him. He couldn’t remember the last time he’d felt like this sharing someone’s heat, didn’t think it had ever felt quite this good, a fully out-of-body experience. The image of it all, Inosuke sitting on top of him, skin red and blotchy with fever and bites and bruises, hair falling in front of his beautiful, drunken face, had Tengen snapping his hips up involuntarily. 

“Be careful,” Inosuke warned, a hand darting to his stomach protectively. 

“You realize you’re on birth control, right?” Tengen laughed. That was pretty much the only thing Aoi insisted on with him. 

“Shut up, asshole, don’t remind me,” Inosuke grunted, stubbornly refusing to move. “Stupid alpha with garbage instincts that can’t even fucking get me pregnant.”

“Hey, don’t go insulting my instincts,” Tengen retaliated, gingerly grabbing Inosuke’s shoulder, pulling him closer without touching somewhere Inosuke would bite him over. “and it isn’t my fault that you can’t get pregnant. Believe me, I’m not happy about it either.” 

Inosuke took the direction happily and circled his hips down on Tengen, bracing flat hands on his pecs. His fingertips pressed in as he adjusted himself, gritting his teeth through hot waves of pressure. Once he was settled, his fingertips flitted curiously down to Tengen’s nipples, laughing when his body writhed in response, his mouth falling open in wordless moans and gasps. His hands pulled and twisted mercilessly, taking great satisfaction in how it knocked the air from his lungs. Inosuke wasn’t afraid to be a bit more dominant, which Tengen expected considering his aggression towards everything else, but it was nice. He was a huge, gorgeous alpha with three wives— getting exactly what he wanted how he wanted it had become expected, but there was always some push and pull with Inosuke. Wild and untamable, never afraid to take the upper hand if it suited him, and that was exactly how Tengen liked it. 

His small, deft fingers rolled and pinched, one or the other occasionally returning to his knotted belly. Tengen just laid back and let Inosuke have his fun, eyes fluttering closed to focus on the constant stimulation. Inosuke was pushed to orgasm again, ass up and falling forward onto his elbows, still giggling brightly to himself, burying his nose in Tengen’s neck, the other craning his own face into Inosuke’s exposed scent gland until all he could sense was the happy smell of cool water and cut green grass. He was shaking unsteadily, and Tengen’s arms moved to hold Inosuke up by the hips, ass in the air and Tengen’s hand cradling under his belly button as he came inside him again, only filling him more. Inosuke drooled with the pleasure of it, his eyes rolling back into his head. Tengen let spit fall into his collarbone, still supporting Inosuke’s weight with his arms and hips.

“You know,” Tengen said once the clouds in his head had begun to part. “If we do this a few heats in a row, I’ll start stretching you out even more.”

“Need it.” Inosuke sighed as Tengen pressed his fingers down into the taut skin, his green eyes tearing up again. In only a few prodding strokes against Inosuke’s sensitive, protruding belly he was shuddering his way through another orgasm, all of his full, dense weight dropping on Tengen again. He was almost surprised Inosuke let him touch there at all, considering how defensive he was of it. 

“Does this make the pain stop?” Tengen asked, guiding hand rocking Inosuke’s hips back and forth. “Need me to take care of you?”

“ Please ,” Inosuke babbled. “It hurts when I’m empty, I need you so bad, never felt this good before in my life.” 

“How much longer you think you have in you?” 

“How long has it been?” Inosuke asked, sounding particularly delirious.

“A whole day, pretty much.” Tengen said. It had been dark outside for hours, and they started this sometime in the early afternoon. 

“Mhm, three more.” Inosuke answered decisively, carefully adjusting himself on top of Tengen and closing his eyes.

“Such a greedy little thing, wanting to keep me for three more days. Maybe I have plans too, you know.” Tengen chuckled. 

“You’re not leaving, right?” Inosuke asked desperately, voice already cracking at the prospect. 

“Of course not, never,” Tengen said immediately. “you know I would never, especially not during your heat. Our first heat together , considering I’m also far too deep in to possibly be able to leave now.”

He pressed his lips to Inosuke’s, part of him feeling a bit anxious to really kiss him for the first time. His lips were dry but soft, pale pink and pressing with gentle insistence against Tengen’s moist, rosy ones. The thought that he should probably introduce Inosuke to the concept of lip balm faded into the background when his pointed little tongue slid between Tengen’s lips, his chest vibrating as he purred contentedly into his mouth. 

Inosuke breathed out a sigh as he pulled away, falling asleep against Tengen with one hand still splayed out across his stomach. It didn’t take long for the sounds of his breath, belly rising and falling with it, to lull Tengen to sleep behind him. 

Neither of them are sure how long they’ve slept for, the window to the outside now filtering in golden light, Tengen on his side with Inosuke curled up into his chest, legs slotted together, one of Inosuke’s hands clutching his yukata caught between their bodies and the other sticking a thumb in his mouth. There’s an intense sense of possession over the small frame attached to his front, wrapping his arms and legs around Inosuke and pulling him in closer. He rutted his hips up into him in slow, stuttering motions, Inosuke’s pussy tight and warm and his . 

Tengen cupped his hand around Inosuke’s jaw, replacing the thumb in his mouth with his own, lips parting to accept it readily. The change woke Inosuke, a light fluttering of his eyelashes as he looked up at Tengen, making a pleased little chirping noise and rocking his hips. The suction of Inosuke’s mouth and the friction he created reignited the flames low in his stomach, Tengen moving to match him. 

“This is so much fun,” Inosuke mumbled around his thumb, chirping again.

“It really is, isn’t it?” Tengen agreed, taking pride in seeing Inosuke all happy and giddy because of him. 

It took everything in him not to claim Inosuke right now, close his teeth around that spot and carry his scent around forever, an endless cool fall night of timber and dried leaves. Was this what it felt like when you fell in love with spending time with someone before doing this? Tengen had never done things in that order before, and it was different, the joy and pleasure and anxiety all a hundred times as intense. This was so much more than right now, it was thousands of hours together over the years, banter and bickering and every cool

rock and shiny acorn Inosuke had ever given him sitting in a pile on his dresser. He’d known, on some level, what the feeling for Inosuke slowly rooting inside of him was , but it hadn’t been something he could accept until now. 

Inosuke’s hand wrapped around Tengen’s torso, nails surely scratching red lines into his back as he rolled his hips lazily. Tengen tilted his head down to kiss Inosuke’s forehead, his bangs split between poking out and sticking to his hot skin.

“I think I’m in love with you.” Tengen said as he pulled away. 

He remembered the thumb housed in Inosuke’s mouth and removed it so he could reply, though he wasn’t sure if he wanted him to. 

“ Oh ,” Inosuke muttered, still wide-eyed. “Me too.”

“Well, glad that’s settled.” Tengen said, Inosuke darting his tongue out to latch onto Tengen’s thumb again. 

Inosuke shrugged, grabbing at Tengen around his neck and his waist, dragging him deeper inside him, already eager to start another round. So Tengen let himself fall back into it, growing delirious as he was sure that all the blood meant for his brain was diverted to his dick.

They lost all semblance of time to the orgasms they traded back and forth, suspended in long, drawn-out moments of bliss. The only indication that days were passing was the light filtered through the windows and the slow swell of Inosuke’s belly, still completely plugged up by Tengen. He looked like he could be pregnant from this perspective, the curve of it sticking out between his legs, thighs pressed upwards as Tengen folded him in half, pleased at the way he could manhandle Inosuke’s flexible body, always in search of a deeper angle to fuck him with.

“Need you to put a baby in me,” Inosuke babbled under him, rocking back and forth. He tilted his head towards where Tengen’s hand was holding his thigh, nuzzling against the scent gland there desperately. Inosuke’s tears spilled from his eyes, overwhelmed with the frustration of being unable to fulfill his strongest instincts. “It’s not fair .”

“Don’t worry, all in due time,” Tengen soothed. “I’m so sorry I can’t give it to you right now, beautiful, it’s breaking my heart too. But you’ve been perfect , so much better than I ever could’ve imagined. Thank you for letting me have you like this.”

Inosuke whimpered softly, salty tears still wet on his cheeks, no real idea what he was feeling, just that he was feeling so much . He trusted Tengen with everything in himself by doing this, sharing the most vulnerable parts of him that came out here. Another version of him never would’ve allowed this to happen, to be weak and needy and uninhibited in front of anybody, much less Tengen. But he didn’t regret it, not in the slightest, because the way Tengen made him feel was worth exposing his raw palms a million times over.

He took Tengen’s hand by the wrist, removing it from where his fingertips were leaving bruising marks on his thigh and placing it over his stomach. The part of him hardwired to protect his womb is terrified by his actions, the audacity of not only allowing someone else to touch him there, but inviting them to. On some level, Tengen seemed to know the weight of the gift being offered, allowing his hand to be led and placed. His spread fingers spanned Inosuke’s belly easily, reaching across his waist from pinkie to thumb, touch feather-light until Inosuke is jerking his body up into his grasp. 

“You feel so tight pretty boy, are you sure you can take it if I come inside you again?” Tengen asked, feeling his knot moving under the skin. He was mostly teasing, but also a bit unsure if Inosuke could actually fit any more inside of him with how deliciously full he felt under his hand. “I can’t imagine how perfect this is going to feel when it’s our babies in there.” 

The idea of it was enough for Tengen to pump another orgasm into Inosuke, struggling to hold himself steady as it triggered Inosuke’s own orgasm. It seemed to have a sense of finality to it, Inosuke’s head falling limp and his eyes rolling back into his head, both his hands anchored on the sides of his hips, shuddering and whining. He looks beautiful like this, thoroughly fucked and glowing with the last of his heat. When he had finally ridden out the aftershocks of his orgasm, he collapsed limply into his nest, any sense of that needy, aching pain fading into the distance behind him.

…

It had been a little over a day since Inosuke’s heat ended, long enough to recover from it for the most part, sleeping for a good twelve hours, getting bathed by Tengen in the onsen and eating enough food for five people. Unlike Tengen, who still kind of feels like he’s been drained of all his blood and is slowly returning to the mortal plane, Inosuke is renewed and refreshed, hopping down the dirt path and chattering excitedly after eating more onigiri than any single person should be able to. 

“Inosuke-san!” One of the kids called out, waving him over frantically. “Beast Hashira!”

Even without any official activity from the Demon Slayer Corps, their membership had still grown marginally. No matter how many years it had been since Muzan, there was no shortage of children orphaned by him or similarly tragic circumstances. They’d taken a few kids in permanently, teaching them about their history and the upkeep of headquarters and bringing them into the family. 

Inosuke probably wouldn’t admit it, but he loved them more than anything, not hesitating to break off from Tengen and run towards the group of three of them. 

“Take down the mountain beast!” Izumi, their de-facto leader of their little group called out, the whole trio rushing Inosuke at once and climbing his limbs like a tree. 

“Die, scum!” Ren shouted, beating his little fists into Inosuke’s shoulder. 

“Ahh, you got me!” Inosuke yelled back, slowly tumbling to the ground. Tengen thought it probably had to hurt a little at this point with the way the kids were just indiscriminately beating him up, but Inosuke just laid there and took it, laughing the whole time. 

“Can you wipe that dumb lovey-dovey look off your face?” Zenitsu scoffed, looking at Tengen with unconcealed disdain. “I can hardly stand to look at your normal expression, this crap is too much.”

“Good morning to you too.” Tengen chuckled.

“Stupid flashy god of idiots, so damn loud in there,” Zenitsu muttered to himself, looking like he was about to say something else when Tanjiro bounded up to them, bright smile ever-present on his face. 

“Hey guys! Is Inosuke-kun doing alright?” Tanjiro asked. 

“You can be the judge of that,” Zenitsu said, gesturing to where the kids were chanting and running circles around Inosuke. 

Tanjiro looked on fondly, always happy to see the kids having fun. They liked him plenty, but he knew Inosuke was their favorite. 

“How about you, Uzui-san?” He asked, turning to Tengen. He’d tried to get Tanjiro to just use his first name plenty of times over the years, but the dumb kid was too respectful. At least one of Inosuke’s friends seemed happy about them ending up together. 

“Yeah, that was a long couple days.” Tengen said. 

“You do realize it’s been almost a week, right?” Zenitsu said back. 

“Damn, for real?” Tengen laughed. “No wonder I feel like I haven’t seen the sun in years.”

Frankly, he wanted to go back to Inosuke’s nest and sleep again, but the ball of energy had insisted on them going out and doing something. He was beginning to realize that was code for Inosuke missing the kids and wanting to make up for being gone so long, not bothering to give his two best friends more than a wave before turning his focus back. 

The three of them sat down at a table outside, just a little ways from where Inosuke was playing with the kids. Tengen found himself tapping a nervous beat onto the wood, feeling like he should be doing a better job of acknowledging the shift in his relationship with Inosuke, getting some semblance of an approval from the people he considered family.

“I’ve liked him for a while,” Tengen blurted out. “and I’m sure you guys are surprised—“

“Bold of you to think we’d be surprised after all the, ‘ Inosuke, come shoot bows and arrows with me, Inosuke, eat lunch with me, Inosuke, set traps with me, Inosuke, let me do your makeup, Inosuke, let’s hold hands and take a romantic walk in the woods,’” Zenitsu cackled, mocking Tengen with a particularly horrible impression of him. This was probably both the worst and best day of his life simultaneously, so Tengen figured he should let him have his fun. “Might as well have been saying, ‘ Inosuke, pretty please kiss me with your gross chapped lips .’ You get a weird sad look if you go a day without seeing him. It’s pathetic .” 

Inosuke shot his head up and turned to where the others were talking. Tengen didn’t think he could hear them from over there, but he wasn’t surprised either, Inosuke always knew when someone was talking about him. “Shut up, Monitsu! I have dry skin!” 

“I think it’s sweet how you always come looking for him, Uzui-san!” Tanjiro piped up, Zenitsu elbowing his side angrily. “Inosuke loves spending time with you too, I think you guys are really cute.”

“But you’re also not surprised?” He asked. Hearing that his little crush had been obvious to everyone but himself was in fact a bit humiliating.

Tanjiro shook his head, grin completely unwavering. “Zenitsu’s being mean right now, but he’s right that you weren’t fooling anybody lexcept Inosuke. But I’m happy for you, plus you guys smell really nice together.”

“Yeah, as much as I hate to say it, I do think you two are quite perfect together in all your dumbassery,” Zenitsu sighed. “You keep him busy, he’d spin himself out otherwise.”

Tengen turned to look at Inosuke, who was sitting on the ground playing some hand-slapping game with the kids. He knew a surprising repertoire of songs, not that he could actually sing any of them, but his gruff little chanting voice was passable. He’d probably call it cute if you got him in the right mood.

“Eh, keeps me busy too.” Tengen shrugged. 

Tanjiro and Zenitsu ended up talking about something else, kind of bored with the topic of Inosuke and Tengen after having enough time to adjust to it before moving on to the next thing. Word had spread between everyone in a matter of hours, mostly at the hands of Zenitsu, who was elated to finally pull something over on two of the people he was most annoyed by on the planet. Tengen found himself getting up, tapping the table twice in goodbye before heading over to Inosuke.

“We need your mask,” Kei told him, a little girl with a habit of taking desperate, panting breaths between every single word she said. “Now I’m going to be the mountain beast and chase them.” 

“Alright, it’s all yours,” Inosuke grinned, pulling his mask off and popping it onto her head. It basically fell down onto her shoulders, far too big and loose on her small frame. 

The other two took off and she started running after them, roaring and bobbing back and forth unsteadily. 

Tengen leaned down, resting his chin on Inosuke’s shoulder. He could smell their mixed scents against his neck, like the cool, fresh air and hardwood floors and plush bedding of a house nestled in the forest, safe and inviting. 

“You’re really good with kids.” 

“I’ll talk to Aoi about the birth control.” Inosuke replied. 

“ Hey , that’s not what I said.” Tengen protested. 

“We were both thinking about it.”