Chapter Text
“C’mon shitty nerd, it’ll be fun. Don’t be a wuss.”
“K-Kacchan, my mommy said I’m not supposed to show anyone my parts down there.”
Katsuki Bakugo scoffed at the freckled, green haired boy shivering below him. He was 11, and had recently discovered porn. He hadn’t presented yet but he was stronger and bigger than all the other boys his age, with the best Quirk in his class. He knew he’d be an Alpha- the coolest, most powerful Alpha ever, even stronger than All Might. And that meant he’d get to pick any Omega he wanted. Not that that mattered. He already knew which Omega he wanted. Izuku Midoriya, the sniveling but adorable little cry-baby brat, who had followed him around his entire life with nothing short of adoration in his big, stupid, green doe eyes. He was soft and submissive, everything the perfect Omega would be, and he was obsessed with Katsuki. Obviously. Katsuki was the best! And ever since Katsuki had stumbled upon knotting porn while looking for free movies on his laptop the other night he hadn’t been able to get those watery green eyes and that plump pink mouth out of his mind. Katsuki didn’t have a knot yet, duh, but he could mess around and pretend anyway.
And he knew exactly how to get his little Deku to give in to whatever he wanted. He was also smarter than the other boys his age, more conniving. He knew how to get what he wanted from most people, teachers and his friends, but most of all from Deku. The boy had snuggled up close with him during all of their sleepovers ever since they were little kids. Katsuki would have to be an idiot to not know exactly what the magic words were to get Deku to give him his way.
He gave Deku his best toothy grin, squinting at him with burning red eyes, hands on soft freckled thighs. “C’mon Deku.” he cajoled, “Don’t you love me?”
Deku’s full mouth quivered. Bingo.
“Of c-course Kacchan…”
Katsuki hooked his fingers into Deku’s All Might briefs. “Yeah you do. I love you too. So you can trust me, ‘kay? I just wanna see.”
Deku nodded slowly, hesitantly, eyes wet and big. He was nervous, but of course he couldn’t deny his Kacchan. He didn’t want him to stop loving him. He wanted to make him happy, like he always did. Plus, Kacchan could be mean when Izuku didn’t do what he wanted. He didn’t like that. “‘Kay. Just look though, right?”
Katsuki chuckled. “Sure.” His red eyes glittered with mischief. He pulled Deku’s briefs down and off, chucking them to the side. He drooled a little at the sight that was revealed to him, toothy grin growing wider. Deku was soft and pink down there too, and Katsuki leaned closer to inspect the little dick, the barely there sack, and hole beneath. Deku was shivering still and Katsuki stroked his thighs comfortingly, like the men had in the pornos he’d watched. Like a good Alpha would. He moved one of his hands to palm his own dick. It was getting hard like it had been from time to time over the last year or so. “Wanna see mine too?” he asked?
Deku perked up a bit, moving up the bed a little under Katsuki. He nodded, biting his full lower lip.
“Heh. ‘Course you do.” Katsuki took his boxers off, showing his hard, bigger dick to Deku.
The little pink mouth popped open and his eyes got wider, like they did when he saw a Hero on tv or walking back from school. “Woah Kacchan! Yours is bigger than mine! And it’s… standing up!”
Katsuki put his hands on his hips proudly. “Yeah! Wanna know a secret?”
Deku nodded eagerly, his nerves forgotten in favor of his signature curiosity. Katsuki knew he would. “I’m gunna be an Alpha when I present! And you,” he pushed a startled Deku back down onto the mattress with a firm hand on his chest, “are gunna be my mate.”
Deku’s eyes got even bigger. Stupid cute nerd. “I am?” he blurted incredulously. “You really mean it Kacchan? How do you know?”
Katsuki leaned over him, rubbing his erection on Deku’s soft tummy. “It’s obvious. You were made for me. Can’t you tell? ‘Cus we love each other. You’re gunna be my Omega.” He leaned down, kissing the shocked, quivering mouth below him. “So you should let me touch you.”
Izuku’s brain was shorting out. He knew he wasn’t supposed to be naked with his best friend right now. He hadn’t thought at all about what he was going to present as, about any of that stuff. All he thought about was finally getting a Quirk and being a Hero, even though the doctors had told him when he was little that he would be Quirkless forever. But Kacchan was smart, he knew everything. And he couldn’t deny the warmth in his chest when Kacchan talked about them loving each other, the little zing that went through his private parts when Kacchan was rubbing up on him and kissing him breathless. Neither of them knew what they were doing, he certainly hadn’t ever kissed before and he doubted Kacchan had either. Which meant that Kacchan was doing this all for him.
When Katsuki pulled away Izuku was almost hyperventilating, but he managed to croak “What if I don’t present as an Omega Kacchan? Will you still love me?”
Katsuki scoffed, gripping Deku’s soft little dick, making the nerd hiccup, his other hand going to Deku’s throat and choking him like he’d seen the Alpha in the porno do. He glared into green eyes, sparks flaring a bit from his hands. Deku whined a little, tears gathering, a deep blush breaking out on his freckled cheeks and chest. The underdeveloped package in Katsuki’s fist jumped a bit. Katuski smiled triumphantly. He leaned down again, crowding the boy below him. He felt powerful. “Don’t be stupid, Deku. You’re a weak, Quirkless, baby. Of course you’re gunna be an Omega.”
Tears poured down Izuku’s face, a deep frown creasing his adorable face. Shit, Katsuki thought, easing up a bit. He felt kinda bad. He wasn’t actually in a porno, and if Deku started really crying he wouldn’t get to touch him. He stopped choking his friend, cradling his head instead, releasing his dick even if it hadn’t quite gone back to being limp- Interesting, Katsuki noted. He nuzzled Deku’s wet cheeks, licking up his tears and shushing him, moving to rub their necks together to scent him like they had done from time to time since they were small. “…and you’re really pretty. And cute.” he added.
Deku sniffed, the tears not stopping but not evolving into full on sobs either. Katsuki squatted over him to rub their chests together and licked his tears again. “Yeah? You mean it?
“‘Course I do.” Katsuki huffed. “So don’t cry, okay? You’re gunna be my Omega even if you’re Quirkless. I’ll keep you safe, okay?”
Izuku hiccuped again, tears still wet on long lashes but not streaking down his face anymore. “O-okay Kacchan.”
“Will you let me touch you now?”
Izuku nodded, a little hesitant but firm. Katsuki’s grin returned. Good. He had to be soft with Deku, he reminded himself. He had to be a nice Alpha so he didn’t scare his little Omega away. He couldn’t actually claim him yet obviously, and if he spooked him too much now he might spoil his chances when they actually presented. Katsuki kind of doubted that, but still. He had to be careful. He would be nice.
He shimmied down, face even with Deku’s bits. His adrenaline was pumping, and now that Deku was willing and pliant, soft thighs falling against the blankets, Katsuki noticed his own nerves. He may have watched a lot of porn, but he had never actually done anything like this before. He had talked a big game, but he didn’t actually have Alpha instincts directing him yet. He realized he really had no idea what he was doing. So, steeling himself, he took a big breath and did the first thing that came to mind. He licked a big stripe up from Deku’s tiny puckered hole all the way up to the tip of his dick.
Deku yelped and smacked both his hands over his mouth, eyes comically wide. Katsuki startled at the sound and shushed him harshly. “Dude!! Quiet!! We don’t want Auntie Inko to hear.”
Deku nodded frantically. He moved his shaky hands away from his mouth a touch, voice just as wobbly. “That felt good Kacchan.”
Katsuki was triumphant again, a bit of his confidence returning. “Yeah? Good. Lay down. I’ll make you feel real good. I promise.”
Deku laid his head down on the pillow, scooting his butt and spreading his legs a little wider. He hadn’t ever felt anything like that before and he liked it. Liked that Kacchan was making him feel good. He was starting to feel warm all over.
Katsuki licked at him more, experimentally poking his tongue into the little furled hole. Deku giggled a little, absolutely adorable, and spurred Katsuki on. After his friend was really wet and drippy down below, Katsuki poked a timid, experimental finger into his friend’s hole. Deku jumped at the feeling and hissed, “Kacchan that’s weird!”
“No it’s not nerd!” Katsuki said, even though he internally admitted it was a little weird to be rooting around the other boy’s butthole like this. But his curiosity was growing, and his dick was starting to ache. “This is how Alphas make their Omegas feel good. You’re my Omega, remember?”
Izuku looked a little unsure. He himself knew basically nothing about mating, except for the extremely rudimentary explanation they had been given in science class that year, and the euphemistic way his mom had explained it to him when he had asked how babies got in people’s bellies. But he reminded himself that Kacchan knew everything. “Okay Kacchan. Just… be careful. I…poop from there.”
Katsuki scowled at him. “Duh, I know that dummy.” But he went back to slowly sticking his finger into Deku’s hole, determined. He kept going, ignoring how Deku’s breathing got heavy and strained, pushing until his pointer finger had disappeared into tight heat. He stayed there for a second, marveling at the sight. He wiggled his finger a little bit, balking at the sheer tightness. Deku made an uncomfortable sound. “Does it hurt?” Katsuki breathed.
Deku whispered back, “A little bit.”
Katsuki kept his finger there, wiggling it more, feeling slightly ridged skin inside, entranced at how Deku’s body seemed to be swallowing up his finger. He wasn’t sure exactly what to do next, but he wanted to keep going, wanted to keep this little experiment up. “Can I try to put another finger in there? Please?”
Deku tensed up more, squeezing Katsuki’s hidden finger. “I don’t know Kacchan. I don’t think anything else will fit.”
Katsuki’s breathing was unsteady. His dick really hurt. He felt really sweaty. “If it won’t go in I won’t do it. I… I don’t want to hurt you. I just wanna see, okay? I’ll be careful, I promise.”
Deku was quiet for a second but ended up nodding hesitantly. Katsuki spit on Deku’s hole, on his middle finger. He tried to poke it in next to the other one, but the nerd was squeezing really tight. He brought a trembling hand up to stroke Izuku’s soft, milky, inner thigh. “Relax, Deku. Breathe. It’s okay. I’ll be careful, okay?”
Izuku huffed a big breath, squeezing his eyes shut even as he willed his body to relax. Katsuki felt the vice grip on his finger ease up and he carefully pushed his middle finger inside until it disappeared too. He stilled there, staring with big eyes at his two sheathed fingers. Both their breathing was labored. He looked up at his green haired friend and his jaw dropped. Man, Deku was so beautiful, he thought. Long, delicate lashes touching his chubby, freckly cheeks, a decidedly pretty blush all over his scrunched up face. His wet mouth was in a little O, and Katsuki thought Deku was so much more stunning than any of the stupid, basic Omegas in any of the pornos he had watched. A still dormant part of him whispered “Mine”, the word rattling around his head, and he stared dumbfounded as his eyes moved down from that precious face to his swallowed up fingers and back again. He swallowed thickly.
“Hey, Deku…you look…really pretty like this.”
Huge, gleaming green eyes opened to meet his. A lip quivered as Izuku smiled shyly. “I do?”
“Oh yeah,” Katsuki breathed. “The prettiest. The best Omega ever.”
Izuku preened at the praise, that gorgeous blush spreading down his whole body. Katuski’s heart ached and, accidentally, a little spark left the fingers buried inside Izuku.
Izuku moaned. Their eyes met, four twin saucers peering deep into each other’s souls. Izuku started to tremble all over, lip quivering again, starting to apologize profusely but Katuski shushed him, rubbing his free hand down his thigh again. “No, no, don’t apologize, that’s good Deku. I… like that. I like when you sound like that.”
Izuku, completely embarrassed, covered his red face, but peeked an eye out through his fingers. “Are you sure?”
“Yeah, definitely,” Katsuki said, trying to stop his voice from shaking. “Hey, Deku, you trust me right?”
Izuku nodded fervently. Katsuki sucked in a breath, daring himself to say the next words. “Will you let me try something else?”
Izuku paused but nodded again. Katsuki slowly pulled his fingers out from the sucking heat of his friend, kissing the slightly open hole when he had withdrawn. Adrenaline was pumping hot through his veins, his head was swimming. But he really wanted to do this. He leaned back on his heels, showing Deku’s bugging eyes how hard his dick had gotten. “I… I want to put this inside you too. I know we haven’t presented yet, but I know we’re going to be mates. And… I want to feel what it will be like when we’re grown up and we can be together forever.”
Katsuki blushed furiously, not meeting Deku’s eyes. When had he ever been so mushy, especially around the nerd? But he meant it when he’d said he loved him, and he really, really wanted this. The quiet but intent part of him that had whispered “Mine”, burgeoning with prepubescent possessiveness, wanted to claim his mate before anyone else could, even if he knew it wouldn’t really do anything right now.
Deku’s mouth fell open again, hands falling away from his face. Katsuki braced himself for rejection, holding his breath, not knowing what he would do if Deku said no. But Izuku whispered so quietly that Katsuki wouldn’t have heard him if he hadn’t been listening so intently, hanging off every single breath, “Okay.”
Katsuki’s heart soared even if he instantly got intensely nervous, more sweat breaking out all over his clammy body. He crushed his inexperienced lips to Izuku’s before his little sweetheart could change his mind, hands holding him so close. It was messy and sloppy, but they were both excited, and he felt Deku’s shaky hands grip his back. He pulled away and whispered, “I love you, Deku, I love you so much.”
Deku giggled happily, legs wrapping around Katsuki’s waist, “I love you too Kacchan. I want to be your mate so, so bad.”
Katuski pulled away, and Izuku sat up a bit, staring at the hanging weight between Katsuki’s legs. Katsuki knew he was bigger down there than the other boys in their grade, he had felt smug about it in the locker room when they had all been changing for gym class. And he felt very proud now with Deku looking at him like that, with what could only be described as hunger on his face. Deku reached a tentative hand out and grabbed Katsuki’s dick, squeezing lightly to feel it, pumping it without really knowing what he was doing. “It’s…bigger than your fingers, Kacchan.”
Katsuki puffed out his chest. “Well duh. Of course I'm bigger than some stupid fingers, I’m gunna be an Alpha, remember? Alphas are big!”
Deku laughed nervously. “I know… I’m just nervous it’s going to hurt.”
“I’ll go slow,” Katsuki assured him. Deku let go of him and Katsuki grabbed himself, nervously lining his dick up with Deku’s hole. He pushed a little, but it didn’t budge, his head just smashing up against Izuku’s butt. He tried again with the same result, eyebrows knitting together in frustration.
Izuku looked at him curiously. “I think it has to be…wet. Right? Like with your fingers?”
Katsuki nodded. “Yeah, you’re right. Do you wanna…put it in your mouth a little bit?”
Izuku nodded, scooting up and eyeing Katsuki’s junk clinically. He opened his mouth and, ever the little try-hard, stuffed the whole thing down his throat.
Katsuki hissed in surprise, and Deku looked up at him, mouth still wrapped all the way around. He moved to pull away but Katsuki frantically shook his head and held his friend there. “Sorry that…fuck Deku that feels so good.” And the view was just as bewitching. Big, shining, green eyes staring up at him, puffy pink lips stretched around his dick. Katsuki decided this was infinitely better than any porn. Incomparable. Absolutely amazing. Intoxicating.
Izuku smiled around him, pleased with himself, sucking experimentally and enjoying the soft sounds his Kacchan made. He wanted to make Kacchan feel good too. He always wanted Kacchan to want him around, to need him, and doing this to Kacchan made him feel ever so needed and special. He decided he loved it. He sucked hard, moving his mouth and tongue around messily, trying to get his beloved friend as wet as he could. Eventually Katsuki pulled away, hands caressing Izuku’s hair, staring at him with reverence. Izuku beamed up at him, spit making his mouth look glossy.
“Fuck Deku, you’re the best little Omega around.” Kacchan’s voice was shaky. Adrenaline was coursing through him again, and Izuku eagerly laid back and splayed his legs out when Katsuki again pushed him down roughly by his chest.
Katsuki took his wet dick in his hand and again lined himself up, noticing how Deku’s little hole quivered as if beckoning him in. He pushed, and this time his head started to disappear like his fingers had before. He gasped, pushed deeper, vision going starry as he encountered the silky, warm, buttery depths. He had never felt such bliss, pushing deeper and deeper until his hips met Izuku’s. He stayed there, marveling at the feeling, reveling in it, staring intently at the spot where they were joined. Heaven, he thought, This is what it feels like to die and go to Heaven.
It was at that moment that he realized that Deku was shivering violently, huge, silent sobs wracking his body. He looked up and saw that Deku’s hands were covering his mouth again, barely containing the pained sounds as fat tears cascaded down his freckled cheeks. Katsuki was shocked out of his reverie. Why didn’t Deku feel good too? The Omegas had whined and moaned and begged when they had been filled in the videos he had watched! He nuzzled Deku’s wet neck, trying to comfort him. “What’s wrong?” he beseeched him, panicking a little when his attempt at scenting didn’t calm his friend down at all.
“Hurts Kacchan. Hurts so bad.”
Katsuki smoothed his hands down Deku’s hips, starting to freak out a little when he still couldn’t calm him down. He frantically kissed hot, wet cheeks, shushing Izuku gently. He wracked his brain, trying to figure out what he did wrong, coming up with nothing. Then suddenly it dawned on him, like a lightbulb. Stupid, he rebuked himself. Stupid, stupid. The omegas in the videos he’d watched had all been female! Deku was a boy. He didn’t have a pussy like those ladies did, maybe male omegas worked differently. Or maybe he just didn’t have one yet because he hadn’t presented? He thought about what he could do to make Deku start feeling good again, and hesitantly reached a hand between them to lightly stroke Deku’s flagging dick.
Deku whimpered softly, but eventually his sobs slowed and he brought big shaky breaths in, hiccuping. Encouraged, Katsuki kissed his swollen mouth, cooing at him, “Yeah that’s right. That’s good, relax Deku. It’s okay, your Alpha is here, I’m gunna make you feel good, okay? Relax.” Katsuki didn’t know exactly where the words were coming from, but they seemed to help, Deku gradually relaxing under him, his dick hardening a bit, his tears slowing.
“Such a good boy,” Katsuki hushed gently, rubbing himself all over Deku, scenting him again. “You’re my good Omega. Just relax.”
With his friend seemingly placated, feeling docile and pliant under him again, Katsuki once again noticed how intensely amazing it felt to be buried in that hot hole. That tight vice grip started to feel painful around him. “I’m going to move a little bit okay? Just stay relaxed, breathe.”
Izuku nodded carefully, and Katsuki gingerly moved his hips back a bit before slowly pushing back in. They both sucked in a breath. Katsuki moaned, oh that felt good. He did it a few more times, Deku just breathing hotly against his neck. Katsuki kept going, thrusts becoming a bit firmer, his breathing becoming labored. His balls felt tight, he felt so so hot, acutely aware of how that tight, sucking channel pulled him back in every time he moved back and forth. He heard Deku continue to whimper softly below him, as Katsuki started to feel something strange pooling in his gut. He kept going, hips starting to stutter, until suddenly he felt a massive release shoot through him, that same dormant voice hissing loudly in his head, “Yessssssssssss”.
Katsuki felt something shoot out of his dick, surprise not dulling the thick blanket of pleasure that consumed him as he collapsed on top of Deku, hips spasming and body shaking. Deku had his arms wrapped tightly around him, nails digging into his shoulders as Katsuki shuddered heaving breaths against his neck. Eventually that golden haze calmed, and Katsuki simply breathed, so relaxed and happy, still buried inside his little friend. Gradually, he shakily leaned back, pulling himself out of the puffy hole beneath him. Deku was shivering. Katsuki noted that his dick felt wet. He felt heavy and sleepy. He looked up at Deku, who was wide eyed and breathless above him.
“That felt incredible, Deku. So so good. Like nothing I’ve ever felt. Did it feel good for you too?”
Deku winced a little, grinning meagerly at him. “I… I don’t know. Maybe a little bit? It stopped hurting as bad after a bit.” He noticed Katsuki’s blissed out expression starting to droop a bit, and he hurriedly continued, “I was happy that Kacchan felt good though! It felt really good to make Kacchan feel good!”
That was good enough for Katsuki. He was so tired. “I think something came out of me.”
Deku nodded gingerly. “Yeah… I felt something.”
Katsuki hunkered down between Izuku’s legs, spreading him a little bit with his fingers. Deku protested slightly, wincing again, but curiosity got the better of him too as he tried to peer down over his tummy. Katsuki marveled at the sight before him. Pale, watery liquid was seeping out of that abused hole. Katsuki stared, gathering a bit of it on his fingers, playing with the thin stickiness between them. He brought his hand up for Deku to see, and they both stared at it, confused.
“What is it?” Deku blinked.
“I dunno.” Katsuki shoved his hand towards Deku’s mouth. “What’s it taste like?”
Deku made a disapproving sound. “Ew, Kacchan. That’s gross. That was in my butt.”
Katsuki pushed his sticky fingers coaxingly against Deku’s pursed lips. “C’mon Deku. It came out of me! You love me right?”
Izuku heaved a sigh, tentatively opening his mouth just the slightest modicum. Katsuki shoved his fingers in his mouth, dragging them against Deku’s tongue.
Deku made a face and Katsuki removed his fingers. “It tastes like pool water,” he said, coughing a bit.
Katsuki shrugged. He grinned devilishly at his Deku, tickling his sides playfully. “It’s my looooove juice” he giggled, smirking at Deku as his friend blushed again and hid his face.
“Ewwwwww Kacchan. You’re so gross.” But that cute little smile was back on his face.
Katsuki felt very satisfied and pleased with himself, and moved up to cuddle into his friend, nuzzling his face into sweaty green hair and smelling the top of his head. He felt so happy. Giddy even. So in love, as Deku nuzzled into his sweaty chest and made a content little sound. Both their eyes had started to close when Katsuki got another idea.
“Hey, Deku, you still awake?”
Deku made a soft little noise of affirmation.
“I wanna do one more thing.”
Deku whined. “Kacchan c’mon, you already put your dick inside my butt. What else could you possibly want?”
Katsuki chuckled. “I know, dummy. Just one more little thing. I promise.”
Deku huffed, exasperated, pulling away from his cozy spot nestled against Katsuki’s chest.
“You’re my mate now,” Katsuki said softly, turning Izuku’s head gently to look at his soft, undeveloped mating gland. He sniffed lightly. Deku smelled like every other kid their age, fresh and generic, but Katsuki told himself he wasn’t imagining the slightly sweet smell underneath that delicate skin, like the milk at the bottom of his cereal bowl. He sniffed again, breathing softly against Izuku’s damp skin. “You’re my mate now, my Omega, so you should have a mating mark.”
Izuku’s breath caught in his throat. He knew they were unpresented, and despite what they had just done a mating mark wasn’t actually possible. But something inside him warmed and made him feel so, so light, so blissful, thinking about Kacchan wanting to claim him for his own. He smiled big, breathing, “Yeah, I guess you’re right.”
Katsuki smiled just as wide, nuzzling Deku’s neck before fitting his small, pointy teeth against the tender, slightly spongy patch of skin where he knew the gland would eventually be. He bit down as hard as he could, hearing Deku mewl cutely, clamping down until he could taste the barest hint of iron in his mouth. He pulled away gently, looking at the already fading but definitely there bite mark he had left. He grinned proudly at his work, kissing Deku’s cheek. “There. Now you’re mine.”
Deku squirmed happily. It had hurt, but he didn’t care. He was happier than he had ever been in that moment. Happier than when his mom had taken him to see the new All Might movie, when she had even bought him a special edition commemorative action figure. He was Kacchan’s.
He tentatively looked at Kacchan’s ruby red eyes. He loved those eyes so much. He loved Kacchan so much. “Can I mark you back? So you’ll be mine too?”
Katsuki moved his neck to the side proudly. “Of course. If your little baby teeth can even break the skin.”
Deku wasn’t deterred. He sniffed Kacchan’s neck and prepared his teeth, dull as they were, just the same as Kacchan had, and bit down as hard as he could.
“Shit Deku, that fucking hurts!”
Izuku pulled away, hoping he had broken the skin. Sure enough, he had. Barely! But he had. He grinned like the giddiest, dumbest nerd Katsuki had ever seen. “Who’s the baby now!”
Katsuki grumbled, shushing him and shoving Deku back into his spot against his chest. He was really sleepy now. He started to drift away, lulled by Deku’s soft breathing and the comforting scent of his downy hair.
Before he fully succumbed to sleep, Katsuki heard a soft, sweet voice. His Deku’s voice, whispering against his chest, “You’re gunna be a really good Alpha, Kacchan. I can’t wait to really be yours.”
Something territorial and primal bloomed in Katsuki’s chest. He grinned wide, holding his soft nerd a little bit tighter to him as he drifted off.