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If ever pressed on it, Katsuki would blame it on Izuku being so easy for Katsuki to smell. They had been play wrestling on Katsuki’s bed, Katsuki tackling Izuku after he’d been a little too pleased with himself over almost nearly beating Katsuki in a video game they’d been playing. It was forgotten now, start menu music looping on repeat in the background, the sun sitting low in the sky as afternoon gave to early evening. Their three parents were still out at work.They'd been playing, just grabbing at and roughly shoving one another in a way that was far too familiar, fun and affectionate in its own way. Katsuki had forgotten his previous annoyance and was more delighted now, especially once he managed to pin Izuku down under him. He shot Izuku a triumphant grin, gloating.Izuku was breathing heavily, eyes sparkling with the same affection and eagerness that Katsuki felt, and it made Katsuki want to hold him tightly in place and win. But Izuku twisted his body, kicked out and managed to scrabble halfway away -- and Katsuki fought to drag him back under him.This was when Katsuki noticed something in Izuku's expression flicker and change. There was something... faintly horrified in the way his eyes went wide, the way his smiled dropped a notch and his mouth slightly parted.This was also when, a moment later, Katsuki smelled him. It was faint and foreign, but Katsuki somehow knew how to place it almost immediately -- it was the smell of Izuku getting slick.Katsuki frowned, confused, but kept trying to manhandle Izuku back under him. That, for some reason, felt like the right thing to do right now. Izuku kept fighting him, but Katsuki half managed it eventually, trapping one of Izuku's thighs between his sharp knees. No matter the situation, play-fighting meant no knees to the crotch. This had been their mama's soft, pleading request. (It'd immediately been bolstered by their mom's sharp, no-nonsense orders that they listen to and respect that request. Their dad had then cautiously asked that no one fight at all, play or otherwise, but Katsuki and Izuku had been completely confused by that plea -- and Mom had laughed at the idea that they'd ever cut it out, while Mama had sighed out similar thoughts on the matter, that they’d never completely stop.)All that meant now was that Katsuki wasn’t worried about their position or Izuku doing anything more to try and get away. And anyway, there were past experiences to back him up -- it was pretty commonplace for Katsuki to end up hovering over Izuku, legs pinning him down easily. Faintly, Katsuki wondered if maybe this had happened before too, Izuku getting wet, and Katsuki simply had not noticed the smell of it. Maybe it had, and maybe Katsuki had just been too focused on their fighting. Maybe...Well, there was no use in trying to figure that out on his own. And anyway, he had Izuku right here under him, looking up at him and shivering like he was dreading whatever Katsuki was going to do or say next. And how was Katsuki not supposed to follow up on that? He loved making Izuku blush in embarrassment and anger. His stepbrother always got so squirmy and fussy when Katsuki worked him up, and Katsuki liked arguing with him when he was like that. He didn't know why, but he sure was going to capitalize on this moment.Katsuki intentionally and dramatically sniffed at the air between him and Izuku, very very audibly making a show of it. Beneath him, Izuku squirmed and glared with the beginnings of a blush on his cheeks, and it made Katsuki want to grin again, triumphant. Pleased.However, in the name of the game, he kept his face as stoic as he could manage. There was a curl of his lip that probably hinted at the fierce and sharp smile he was holding back, though."What's that smell?" he asked pointedly, sniffing again, leaning in closer to his brother.Izuku began to flush all over now, but otherwise put up a good front. He made another attempt to get from under Katsuki, but it didn’t do him much good. Oddly, Katsuki noticed, the smell intensified slightly."I get it, you win,” Izuku grumbled, turning his face away a little, glaring at Katsuki out of the corner of his eye now. It made Katsuki want to bite him in the face, teeth tingling with the urge -- but it wasn't an angry urge. It was vibrant, whatever it was. A humming, thrilling, intense feeling that threatened to punch the breath out of Katsuki.Beneath him, Izuku shifted as if testing to see if he could maybe get away, but otherwise did nothing, still glaring. “Kacchan, you win. Get off of me."Not like asking or demanding was going to work -- Katsuki was too invested, and people trying to order him to do things had never been particularly effective. It usually just made him want to sink his claws in deeper, when someone told him to stop or to chill out or to calm down. He knew Izuku was fully aware of that, too.So instead, Katsuki leaned in close and took a deep breath, making a show of huffing in Izuku's scent. He let a hint of that ‘I win’ grin peek through after all, far too pleased with himself not to. Still, he stayed as stoic and serious as he could manage, demanding lowly, “What's. That. Smell."The smell got stronger yet, and Izuku blushed more, struggled much much more. He didn't really seem to be trying to get away, though -- just as Katsuki was making a show of sniffing Izuku, Izuku seemed to be making a show of how he was trapped beneath Katsuki.Something about that had Katsuki's veins coursing with fire. He wouldn't get slick like Izuku would (and was, laid out under him), but Katsuki felt a stirring in his groin that wasn’t... completely new to him. He wasn’t a child anymore, now on the cusp of middle school. He knew a few things about what that meant. About what Izuku smelling of slick had to mean.Izuku knew he did, too. "If you smell it, then you know what it is," Izuku said very quietly, stubbornly not playing Katsuki's game, even as he was turning redder and redder -- and why was that so attractive to Katsuki? Why was that making him want to rub up against something? Maybe up against his brother, who was the nearest thing and was inspiring these feelings in the first place. The warmth and smell of his body certainly were inviting..."Do I, now?" Katsuki challenged back, and it meant more squirming and blushing from Izuku. Which in turn meant more of Katsuki feeling everything centralizing between his legs. He could barely remember to keep his knees gripping on Izuku's legs. Not when there was this strange urge, this faint vision, to instead loosen his hold and nudge Izuku’s thigh tight up against his crotch.But Katsuki figured he should focus on messing with Izuku. It made him feel good and was a decent distraction from his spiraling thoughts. "I dunno, Deku. I’m an alpha and you're an omega, so maybe there’s all sorts of stuff about you I don't know about."It was quite the bold assertion, what with their parents making sure their different alignments weren't an excuse for ignorance -- and additionally with Katsuki and Izuku spending nearly all their time together. What it was, then, was an outright lie. And they both knew it.But Izuku was breathing heavier now, looking simultaneously mortified and intrigued about Katsuki playing dumb and trying to make Izuku say the condemning words about his own wetness. What a little freak. Katsuki remembered thinking that same exact thought when he'd first met Izuku, back when they'd been 5 or 6. That was back when Katsuki’s mom and dad had let him know they were dating the woman who eventually married them later that year and was now, easily and naturally, his mama.Even back then, meeting this kid who Katsuki would come to call his freak little brother, Katsuki had figured out that Izuku was weird. It was something that drew Katsuki in, because ‘*how* weird?’, and ‘why?’ were always the questions on the tip of his tongue. Katsuki had yet to be disappointed by Izuku's idiosyncrasies. Now, Katsuki almost always looked for them.This, right now, was another one of those idiosyncrasies. Those weird Izuku moments. Why was he getting wet? Slick happened when you wanted sex, Mom had said. And sex was... well, something that Katsuki had an admittedly loose grasp on, but he knew that people did it to make a baby, or sometimes to feel good.What about all this made Izuku want sex? Who'd he wanna make a baby with? Katsuki? Katsuki snorted at the idea of it. The two of them, biologically, couldn't.But maybe it was about wanting to feel good. And that... that, Katsuki was slightly interested in, as weird as it was when he stopped to think about it. He wasn't sure how they stumbled into this situation, but already Katsuki was feeling maybe a little good. Definitely like he was craving more.Okay, fine: really, he was super interested in this, as Izuku shimmied to prop himself up on his elbows and stared defiantly up at Katsuki. His head was tilted back and his neck was craned up as he whispered, intense as ever, "You know everything about me."Katsuki stared down at Izuku, just as defiant in turn, something exhilarating about them glaring each other down. The twilight was firmly here, light fire-bright and golden as it flared in through the window. Bathed in that light, Katsuki felt emboldened. Felt like he wanted to kiss his brother. But that would mean breaking this stare. That would mean taking a leap of faith that Katsuki was sure would kill him if it turned out to be in vain.Izuku, somehow reading Katsuki's mind, something he seemed to do often (though Katsuki would never admit it out loud), strained to push himself up more, stretched up as high as he could, and pressed a chaste kiss to Katsuki's chin.Katsuki blinked, stunned and frozen in place as Izuku settled back down, still holding himself up with his elbows. He looked so pleased with himself, and it made Katsuki want to do -- something to wipe that look off his face.But Izuku just shocked him further, by giving in after all. "It means I'm wet," Izuku said in that same little whisper, winning their stare down by throwing Katsuki completely off guard with the admission. "That smell? I'm wet down there, Kacchan."Katsuki growled, full of sudden restless energy, feeling like he might burst at the edges, blinded by the setting sun's rays of light and his brother beneath him. At a loss for what to do, Katsuki followed his most immediate instincts. They had him shifting and bending down to bite at Izuku's cheek, because it just felt like the right thing to do.It wasn’t a hard bite, just the pressure of his teeth closing together. A claim. Izuku squeaked a little, but stayed still and let him do as he pleased. So Katsuki pulled back, and pressed his lips firmly to the saliva dampened skin of Izuku's face. It made his words muffled, as he asked, "Why?"Izuku sighed out gently. Then he wriggled around, until he slotted Katsuki's leg up against his crotch -- a perfectly reversed match to what Katsuki had been envisioning only a few minutes earlier. Katsuki's heart went double time, gaze dropping down between them to watch as Izuku began to softly hump up against his thigh. His eyes didn’t leave Katsuki's when Katsuki looked back to his face."I dunno. It happens sometimes and I don't know why," Izuku admitted. So they were going to openly talk about it now that Izuku was dragging himself against Katsuki's leg, huh? This was all much more than Katsuki had been intending for, when he’d started this warped game of asking rude questions he’d already known the answers to. Izuku was beginning to pant, and the smell of wetness was becoming less distant. It was starting to smack Katsuki right in the senses, his nose keen to hone in on it."Weirdo," Katsuki accused lightly, not particularly meaning it this time. He was enjoying watching Izuku make a fool of himself on his leg. Liked the feeling of him humping against it.Also... well, Katsuki knew what it was like to get inexplicably strange sensations for no reason. He got them too, sometimes. They were identical to the way he was feeling now, need tingling in between his legs. Right now those sensations were more incessant than they’d ever been before, as Izuku rubbed himself up and down Katsuki's leg and let out tiny panting breaths.However, this time it wasn’t inexplicable but instead was a sex thing. Katsuki knew, still as vague as ever but definitely knew, that it had to be -- had to be the thing where people wanted sex and did it because it felt good. Right now, he felt good. He wanted to feel even better, and he had an idea of how to manage it.Suddenly, Katsuki realized -- he wanted to see. He could smell Izuku's special place getting wet with slick, and he wanted to see it, too. Maybe touch it. That was normal curiosity, wasn't it? And maybe Katsuki could figure out what was happening to Izuku. Maybe he could figure out what was happening to himself, too."Let's take off our clothes," Katsuki decided firmly. Izuku wasn't going to agree if it was just him, so it had to be both of them. "I wanna help.""H-huh?!" Finally, Katsuki got the upperhand here, and Izuku stopped humping Katsuki's leg to stare up at him in a dazed confusion.The sound of the video game music played on in the background, and Katsuki wondered why it was making this all less surreal. Katsuki felt like he could figure this situation out, instead of being overwhelmed by the newness of every single part of it."I'll look and see what's going on with you," Katsuki explained impatiently, pulling away to start undoing the button and zipper on his jeans to wriggle out of them. "Come on, little brother."Though there were only a few months between them, Izuku always blushed and smiled this nearly smug smile to himself when Katsuki called him that. It was so weird, but it also made Katsuki feel oddly proud about it, too. Maybe because it was true: Izuku was his little brother and no one else’s. So Katsuki carefully laid that claim on him in rare moments, savoring it and keeping it special between them.Well, there went Izuku beneath him, blushing and smiling like usual. He was so agreeable for Katsuki when he chose to be. "Okay," he relented easily, sitting up to start undressing too, still panting and smelling... really really wonderful to Katsuki.It didn’t take long, not with them as eager as they were. Once they were both naked they assumed similar positions as before, Izuku on his back and Katsuki hovering above him on the bed. Now, as the bright twilight began to fade into the more muted portions of the late evening sunset, as Katsuki kneeled completely nude on his mattress, the bed covers soft and feathery on his shins and knees -- now, Katsuki could feel a sense of nervousness begin to grip his heart.He focused on his movements, on reaching between Izuku's legs to spread his cheeks and get a better view. He wondered if it felt bizarre for Izuku to be laying on top of the covers with nothing on. That thought fled away, unimportant to Katsuki when Izuku immediately flinched and gasped at his touch. It was like Izuku didn't know how to react to what was going on.Honestly, Katsuki felt the same, but he was swallowing that down, trying to appear in charge. They weren't babies anymore, now in their last year of elementary school. Katsuki had long been training himself to not act babyish when things were strange and new and perhaps overwhelming. He could put on a brave face for the both of them, if that's what it took. This still felt like the right thing to do, the right avenue to follow, so Katsuki pressed an inquisitive finger to Izuku's special place. This was a place full of mystery and intrigue for Katsuki, especially after finding out that it was a little different between alphas and omegas. That here was a place their moms and dad had warned them about protecting, about telling an adult if a stranger ever tried to touch them here between their legs.Katsuki and Izuku weren't strangers though, so Katsuki spread him a little wider to see as he touched. Izuku whined and made to wrench away, but Katsuki could smell the slick. Could see the way Izuku pulled away slightly, but then how his hips less subtly moved back, seeking, towards Katsuki's hand.Katsuki felt intoxicated from the heady, potent whiffs of Izuku's wetness now, and he wanted to feel it on his hand for some reason. The thought alone made him shift, antsy, his penis feeling weighty between his legs. This was all so strange and new, and Katsuki advanced forward bravely.He pressed a little harder to the soft puckered skin of Izuku's special place, and used his other hand to cup Izuku's heavy balls carefully. Katsuki had noticed during baths with their dad, an activity they had only stopped doing together last year, that Izuku's had been getting bigger, looking swollen to Katsuki. He'd been wondering if they were sensitive, and figured this was the time to find out. Izuku didn't react too notably, though he whimpered and his thighs and -- quite surprisingly -- his penis twitched minutely at the touch. Katsuki's gaze naturally drifted from Izuku's balls to his erect penis, and he gazed wonderingly at it, intrigued.Izuku's penis wasn't too different from Katsuki's, though Katsuki did notice the skin around Izuku's tip covered more of it than Katsuki's did of his own. Katsuki took a moment to look down at his own penis and the way his tip was pink, the skin tight around the head. He knew it was different in another way, though. A big, big way.For Katsuki, the skin at the base of his penis was scar-shiny and elastic-soft. Just like Katsuki knew about Izuku's slick as an omega because their dad and mama had explained it, he and Izuku had learned about alpha knots because their mom had explained that. So Katsuki knew this was where his knot would be, once he started getting them. He hadn't yet, not really. Not real ones.Beneath Katsuki's hands, Izuku fidgeted hopefully, and whispered out, "Kacchan?"It made Katsuki remember himself and what he was doing. That Izuku, laying here in the fading sunlight, was waiting for Katsuki to take the lead and push onward. So he ran a thumb down the center of Izuku's sack, smiling when Izuku let out a breathy little, "H-hah," and said nothing else."What," Katsuki breathed out, quiet, quiet. He was feeling the utmost affection for Izuku right now. "What, little brother?"Izuku only whined in his throat and Katsuki was overcome with the intense and sudden desire to both scent and be scented by him. Katsuki let go of Izuku's balls and began to rub his wrist and the scent gland there against them instead."Wanna smell like me, Deku?" Katsuki borderline teased, eyeing the way a few drops of clear-ish fluid began to dot the tip of Izuku's penis at the scenting. Izuku smelled so incredibly wet now.When Katsuki pushed his finger to Izuku's special place a tiny bit harder, it was enough pressure to make a little of his finger slip inside. He immediately could feel slight dampness wetting his fingertip. Something swooped low in Katsuki's tummy, and it almost felt like he couldn't breathe around it. That was Izuku's slick he was feeling. Something about that was breathtaking.Katsuki rubbed his wrist gland more fervently to Izuku's swollen balls, amazed. "Oh. You really like that.""Y-yeah," Izuku breathed out, hips jumping away from and then fully back into Katsuki's touch. "Want me to do you?" Izuku asked softly. He held up both hands, fingers curled into loose fists, wrists extended outwards, leaving himself completely vulnerable.Katsuki felt his penis twitch intensely and a desperate twinge stir deep in his gut that made him suck in a tight breath. Yeah, he wanted that. More than anything. Katsuki leaned in and rubbed his cheek to one of Izuku's wrist, and reveled in the way he could smell Izuku's soft scent washing over him, sinking into his skin."I should stop. Moms and Dad are gonna freak," Katsuki mumbled as he absolutely did not stop. Their parents had never liked the two of them unintentionally scenting each other as often as they did, spending so much time together and play-fighting all the time. And that was normal stuff -- family certainly didn't scent like this."I can do it somewhere else," Izuku said agreeably, even with his voice so faint and his attention focused mostly elsewhere.Katsuki shook his head, still nuzzling into Izuku's wrist, drinking in the sight of him sprawled out on the bed. To Katsuki, it looked like this was exactly where he'd always belonged: right here in Katsuki's bed. "Like where?" He challenged his brother, not wanting to stop but knowing he really needed to.Izuku dropped his hips low against Katsuki's touch, though Katsuki's hands between his legs had stilled as he carefully regarded what Izuku was saying. Smiling, Izuku answered with, "Like where you're doing it to me. Moms and Dad won't notice down here. Not under our clothes."Izuku was right. And when Katsuki thought about that, he could feel a tightness in his knot-skin, all achy throbbing and strange pressure. It made an idea spring to mind."You wanna -- wanna do it on my knot?" Katsuki asked, grinning and posturing, heart going triple time now as he dragged the inside of his wrist against his brother's balls.He really didn't have knots yet. But he could feel the beginnings of swelling lately. He wanted to see how big it was gonna get today. And he wanted to see how wet Izuku was gonna get, too. Maybe not as wet as he would one day -- which, thinking about that made Katsuki realize he couldn't wait to see how wet that'd end up being -- but still. Still.Izuku groaned softly, mouth falling open and tongue lolling out like he wanted something in there. What, did he want Katsuki's knot in there? Katsuki hissed as the base of his penis swelled a little at the thought. He was hard, uncomfortably so, imagining Izuku lapping at his knot. Imagining his penis pushing into Izuku's mouth -- or into Izuku's wet special place."Yeah," Izuku murmured demurely, eyelashes damp and clumping together with tears that had sprung up at some point, his pupils blown dark and huge as he looked up at Katsuki. "Yeah, I'll do it on your knot." There was a dribble of slick threatening to drip down the inside of his thigh from around Katsuki's finger. It was driving Katsuki crazy."Lemme finish with you first," Katsuki said gruffly -- and he didn’t know what exactly he meant by that, but knew that yeah. Yeah. He was gonna follow his instincts and... yeah.Izuku seemed to agree to it, and he let Katsuki roll him over onto his stomach with no resistance, the two of them still connected with Katsuki’s finger curled into him. The movement made a faint squelching sound, as Izuku moved around on that finger, and both of them moaned softly at it.Katsuki wriggled his finger in a bit deeper, watching the line of slick drip out a little more. Izuku panted and squirmed and used his knees as leverage to push back, and Katsuki suddenly had a vibrant thought of slotting his penis between Izuku’s cheeks, of feeling that wetness against himself where he was hot and hard.But he wasn't willing to give up on this fingering business yet. Not when Izuku looked so good and enticing, now moving back against him in little stuttering bursts of movement.Katsuki felt like maybe -- maybe he should put in another finger. One wasn’t enough; Katsuki felt oddly adamant about that, a yearning for more gnawing at the core of him. Izuku’s special place would stretch even more around a second finger, wouldn't it? Katsuki wasn't sure, but... down here was wet and soft and enticingly pink. There had to be more give.“Do you want another finger?” Katsuki asked, when he usually would have just done what he wanted and told Izuku as he was doing it. That didn’t... sit well with Katsuki for some reason, not with what they were doing right now. All of this felt a little different than anything else they’d ever done. So, it felt right to ask -- though Katsuki couldn’t help but half scoff and follow up with, “Think you can take it, Deku?”Izuku whined, propping himself up more on his knees. His hand was groping wildly away from him, until he found and then grabbed a pillow, shoving it under his hips and immediately rutting down into it near-violently.“Uh-huh,” Izuku said, breathy, rolling his hips into the cushion and forcing Katsuki to go along with his movement. The jostling made it easy for Katsuki to follow the momentum, and the next thing he knew he was pushing his finger rhythmically into Izuku, thrusts going from shallow to deep and back again, finger in up to the knuckle inside his brother. “Please, Kacchan, please.”“You’re such a weirdo,” Katsuki muttered out, at a loss for what else to say.He had to take his other hand and hold on to Izuku’s hip, pressed him down and forced him flat against the cushion to hold him still. Izuku was still wiggling, trying to slide himself forward and get friction desperately. Katsuki kind of thought he looked pathetic, but in a good way. In a way that was getting Katsuki hotter, his penis getting even more uncomfortably hard and tight, so tight, around the base.“Ugh, so weird,” Katsuki said again for emphasis, maybe trying to convince himself that it was just Izuku who was desperate and pathetic here. Or maybe he was inadvertently talking about himself, too.While he held Izuku down, he carefully pulled the one finger out, and Izuku moaned out high pitched and faint. There was an obscene squelch as the grip of Izuku’s hole didn’t seem to want to let Katsuki go.Katsuki sucked in an involuntary breath, staring at the way Izuku’s hole glistened with wetness, the view no longer obscured by his hand. His brother's special place fluttered, opening and then tightening around nothing, and not even Katsuki’s hold could stop the way Izuku slammed himself against the pillow in jackrabbit quick thrusts.“Hey,” Katsuki objected, leaning more weight against Izuku. “Hold on.” It seemed important that he waited -- for what, Katsuki wasn't yet sure. But Izuku squeaked, pitiful and mournful, which Katsuki took to mean that he was trying his best to stop -- but just couldn’t.That... could be fine, Katsuki realized, catching a glance at the way his finger was shiny from being inside his brother. It immediately entranced him, and Katsuki stared at the way the slick coated his finger filthily. He couldn’t help but hold it up to his nose and take a long sniff.The smell was potent, clinging to Katsuki's skin. It perfectly matched the formerly faraway smell of wet that Katsuki had picked out earlier this evening. Back at twilight.Now, the sun's last fiery light was nearly completely gone, and the cool blue light of evening sliding into night took its place outside their window. There were crickets in the distance. The start screen music of the long forgotten video game hummed in the background. And Katsuki was sniffing that smell up close. He was starting to think that he’d never forget it for as long as he lived.Before, it’d been strange but intriguing. Now, Katsuki didn’t know what he’d do with the memory and knowledge of this smell, of Izuku's most private and intimate smell. Knowing like this felt big and important, like something amazing that he was going to carry around with him, always.Beneath him, Izuku was still humping the pillow and keening softly. This was all so much, Katsuki was feeling so much, and he said, without thinking and still sniffing his finger in deep huffing breaths, “You smell good, Deku.”Izuku’s rutting slowed and he craned his neck back, eyes wide in vague confusion, though they were also slightly out of focus as he chased his high. With his hips already slowing because of his position and confusion, Izuku took a couple of deep breaths before he finally did as Katsuki had told him earlier and stopped thrusting against the pillow.He eyes went even wider when he realized what Katsuki was up to. “Don’t -- ” Izuku propped his rear up slightly and swayed it a little (Katsuki wondered if that was on purpose or pure coincidence or instinct or what). “I thought you were gonna put another one in. Don’t smell that, that’s gross -- ”Katsuki glared. With Izuku’s special place winking up at him like it was, it was hard to focus on looking him in the face. But Katsuki managed it. “Don’t tell me what to do.” He countered lowly. "And it's not gross, shut up."Because of their positions, Katsuki suddenly remembered his impulse from earlier. It seemed like a waste to not try it now. Katsuki took his penis in hand, trailing the slick-damp finger over the slitted head of it, then along the underside of his length. He kept going until he stopped at the knot-skin, rubbing the residual wet from Izuku into the soft skin there. It sent a fire through him, feeling right and perfect and like it was precisely what he was meant to do.Izuku was blushing but he was staring, unwavering, at Katsuki, eyes tracking his every movement and mouth slightly agape. Katsuki shuffled in closer on his knees. He spread Izuku’s cheeks apart and then very delicately pressed the full length of his penis between them.Izuku gasped audibly, and he bucked back against Katsuki, his heat and his wet more enticing than anything Katsuki had ever known. If Katsuki had thought a finger's worth of slick to his knot had felt good, it was nothing compared to being firmly pressed up to the source of that slick. For a moment, while thrusting up to chase that soft and wet heat, Katsuki thought he might lose all composure. He thought he might just keel over and die from how good it felt.“K-kacchan,” Izuku stuttered out, eyes half shut, a glazed look coming over his face. He tightened up around Katsuki and they both cried out pathetically from the sensation. “Oh, oh, Kacchan, inside, inside me.”Katsuki normally would have rolled his eyes at Izuku’s one-track mind. But right now he understood and sympathized. He was torn between giving Izuku exactly what he wanted -- there was something deep and subconscious in him screaming that he needed and had to give Izuku whatever it was he asked for -- or chasing the heaven they currently were in. Katsuki’s penis was twitching and his knot had swelled to the largest Katsuki had ever seen it, the base looking engorged and fatly rounded.“Kacchan,” Izuku implored again, impatiently pressing back against him. Then, he lifted himself up even more with his knees, straining, until the blunt head of Katsuki’s penis caught on Izuku’s slippery rim. It was maddening and manipulative, but Katsuki found that he didn't care that the choice had been made for him. He immediately took his length in hand, and prodded the head to that little, winking hole.“Yeah,” Izuku breathed out. “Please put it in.”Katsuki had no experience with this thing they were doing, wasn’t at all sure how to proceed. But Izuku wanted him inside, and a hundred thousand things in Katsuki were screaming that there was something akin to winning and success and perfection in thrusting himself fully into his brother.“Okay,” Katsuki conceded, more easily than he had ever agreed to anything. With one hand holding Izuku’s hip, and the other firmly gripping his length, Katsuki tried his best to ease it in. It was more difficult than he'd thought it'd be. Izuku’s special place was slick and soft, but it still resisted as Katsuki tried to enter.Izuku dropped his head forward and wiggled impatiently as Katsuki tried to line them up and push inside. His penis glanced off the puckered skin and Katsuki growled in frustration.“Kacchaaaan -- ” Izuku whined, and Katsuki growled again.“Just wait,” Katsuki snapped, then lined up again and very, very carefully tried. This time, he pressed the head to the hole and the tip worked in. Izuku let out a shriek and instantly tightened around him, and Katsuki --Well. The hot, wet pressure around his tip was already overwhelming. His brother was so much wetter inside than he looked like he was on the outside, leaking out just a misleading few dribbles of slick. Now inside, no matter that it was only the smallest bit, Katsuki could understand how much more slick Izuku would drip out from here one day.If he was this wet inside now, but was like Katsuki with his knot and wasn't fully developed yet -- it was going to be amazing. It was going to be soaking wet down here, one day.These thoughts, how completely amazing Izuku felt squeezing around Katsuki's tip, the sight and the smell if Izuku’s wet already clinging to Katsuki’s skin, to his own most private places -- Katsuki's penis wasn't even deep enough in Izuku to be past the ridge of the head, but he was done.His belly clenched and fluttered wildly, and the indescribably good feeling that Katsuki knew from other attempts at chasing the stirring tightness of his groin began to wash over him. This meant it was all just about over. And Katsuki couldn’t even care, it all felt so good.Because he was buried, however barely, in Izuku, Katsuki couldn't see the way his tip dribbled out clear, jellylike fluid -- but he knew from previous experiences that it must have happened. It usually did when he chased these kinds of feelings to their culmination. Izuku was slick enough inside that it really didn't matter, Katsuki's meager contribution to the wetness. But something about knowing that it came out, from inside him and into Izuku... Katsuki groaned and his hips kicked forward just a bit.Izuku was whining unintelligibly and lowering himself slowly back onto the pillow. Katsuki, figuring that Izuku was probably muttering about the little bit that Katsuki had managed to get and stay in him, made sure to follow, keeping them connected by the hot wet heat of Izuku's special place.“Stay in,” Izuku finally managed to mumble out, sounding delirious and grinding furiously into the pillow once more. Katsuki was amazed at how Izuku’s movements made his rim shift and squeeze around Katsuki’s tip. More slick bubbled out from around where Katsuki was plugging him up.“Kacchan, K-kacchan...!” Izuku thrust hard and fast against the pillow for about thirty seconds more, breath so labored and pained that Katsuki almost thought to worry, if it all didn't look so good -- and if Izuku wasn't so obviously chasing pleasure. Then Izuku, hips dropped flush to the cushion and rim clenched, stilled and gasped for air.Katsuki winced as the tautness of Izuku’s body made his penis pop out unceremoniously. He stared in amazement though, as Izuku groaned shifted beneath him -- because Katsuki’s tip was coated in Izuku’s slick. And Izuku’s special place was slightly gaping, just a little, as more wetness trickled out, smears running down the creasing of Izuku’s inner thighs.The smell from before was nothing compared to the smell of now. Both of their scents were mixed together with one another. They’d have to shower and change clothes and the bedding before their parents came home. They’d have to...Izuku peered over his shoulder, eyes teary but whole body boneless and relaxed. His voice was soft and awed, somehow demanding all of Katsuki's attention with no effort at all. “Can we do that again? Later? Or -- just, again, sometime?”Katsuki, who hadn’t gotten far enough to think about anything past needing to clean up, realized with a start that there was no doubt in his mind that they would. Doing this again was a given. It'd been too good. It'd meant too much.“Of course,” Katsuki told Izuku confidently. “Why not?” Katsuki grinned and took his penis in hand to show Izuku the way his tip glistened with Izuku’s wetness. “Look, you scented me after all.”Izuku flushed, both in happiness and in embarrassment, but he openly smiled and wiggled his hips happily. And Katsuki, grinning and sitting back on his haunches and feeling more sated than ever before in his life, shared the sentiment.