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Katsuki told them not to tell Deku.
He told every single one of those dumb motherfuckers that, not only must they not tell Deku, they must not tell anyone, lest Deku find out through the grapevine.
It was his only condition.
The first time it happened was the only time he didn’t set the condition beforehand, because it took him by surprise.
It was after the sports festival, in a hidden alley in the vast stadium. Everybody had been giving Katsuki shit about how he acted on the podium, but not Kirishima.
Kirishima told him he thought it was manly, dragged him away from the others, and then he got on his knees and sucked Katsuki off.
Kirishima let Katsuki cum in his mouth, but he spit the stuff out on the ground afterwards. Then he tried to come up for a kiss, but Katsuki pushed him away.
“Fuck off, Shitty Hair, not interested.”
“Hah! Wow, ok. That’s fine. I guess you didn’t ask for that.”
“No, I fuckin’ didn’t.” Katsuki looked away and then mumbled, “Was good tho.”
“Wanna do it again sometime?”
“We’ll see, Hair-for-Brains. Don’t hold your breath.”
Kirishima grinned.
“Wouldn’t want to! You smell so manly, Bakugo, like barbecue chicken or something -” Kirishima leaned in for a closer whiff, but Katsuki shoved him off.
“The fuck?”
There was a little breeze in the alley; it tickled the back of Katsuki’s neck and made him suddenly paranoid that someone could have been watching them, listening.
Not someone. Deku.
The coast appeared clear, but Katsuki lowered his voice as they started walking out of the alley, back towards their classmates.
“Listen, seriously… Kiri-kun.”
That got his friend’s full attention.
“Don’t fucking tell Deku about this. Don’t fucking tell anyone. Deku cannot find out.”
“What? I mean, sure, but why are you so concerned about him knowing?”
Katsuki thought back to the incident with the sludge villain. Deku nearly died for him without a second thought, without a chance for victory. Deku had been stuck to Katsuki like a barnacle since before he could remember, no matter how hard he tried to pry him off.
They both had so many mixed up feelings about each other.
And now Deku wasn’t the skinny quirkless kid he used to be; he had some unpredictable borrowed killer power.
“I don’t wanna find out how he’d react. He’s weird about me.”
“Ha! He’s weird about you? That’s kinda rich, bro.”
“Shut it, Shark Face. You don’t know the fucking half of it.”
After that, Katsuki always made the guys agree to his terms ahead of time.
Kaminari found it amusing.
“Oh, why, because you looooove him and you want him to think you’re saaaaving yourself??”
“No, idiot. He’s completely insane and obsessed with me. It’s for your own damn safety. You agree or not?”
Kaminari agreed.
Katsuki lost his virginity giving it to Kaminari in the ass like he’d begged him to. Kaminari released tiny electric jolts throughout his body, which had not assisted Katsuki’s virgin dick in lasting more than five minutes (which it did not).
Sero hadn’t seemed very surprised by the request for nondisclosure and agreed easily, without batting an eye; it made Katsuki suspect that Kaminari hadn’t kept his mouth shut.
Damn, Katsuki knew he shouldn’t have trusted that loudmouth, but it’s kinda hard to say no when somebody comes around looking for you to take his virginity and lose yours.
Wait, had Kirishima told Kaminari about the…?
Regardless, Katsuki and Sero sucked each others’ dicks. It was a great time.
After that, guys kept coming around begging for it. They’d obviously heard that when it came to hooking up, Bakugo Katsuki was fun, casual, discreet and up for almost any offer. He had a great dick (it would have been respectable even on an alpha, but for an omega it had to be in the ninety-ninth percentile for both length and girth), and he smelled delicious, even to other omegas.
Word got around on who to call for a good time. But the word came with an insistent asterisk.*
*Don’t tell Deku.
And that statement came with a parenthetical.
(or obviously anybody who might tell Deku!)
That meant nobody told Iida or any of the girls.
Nobody told Mineta or Monoma, who would both have been only too eager to spread the word that Explodo-Boy of all people was the designated UA school slut, especially since there was no chance Katsuki would ever touch either of those cretins.
Katsuki wondered sometimes if he was being over-vigilant, if maybe Deku would learn that his childhood friend sleeps around now, and he’d react like a normal person.
Something in Katsuki’s gut told him otherwise.
Something buried even deeper hoped otherwise.
Part of Katsuki’s concern was because Deku remained unpresented; technically, that meant Deku was still a child, while Katsuki was an adult - a sexually active omega to Deku’s virgin pup ass. Katsuki relished that he was still definitively ahead of Deku in this category, at least, but it worried him that Deku was so out of his depth when it came to sex.
Katsuki sometimes found himself wondering… when Deku finally presented, would he find Katsuki sexy like other guys did? Would Deku think Katsuki smelled good and want to suck his dick or get fucked by him, or even want to fuck him, once Deku was a real man? Or would Katsuki’s past behavior preclude Deku from noticing his obvious allure?
Katsuki had once been deflated about his presentation as omega, until he realized that it just made him more of a stud. Male omegas couldn’t get pregnant, and they couldn’t get anyone else pregnant. Academics theorized that male omegas evolved to help prehistoric alphas release pent-up sexual energy without overpopulating their communities...
Whatever.
In addition to Kirishima, Kaminari and Sero, Katsuki would also hook up with Ojiro, Sato, Shinso, Shoji, Tokoyami and of course, Todoroki; plus most of the good-looking guys in 1-B and the rest of Class 1, as well as Tamaki from third year, and then a little parade of other third year guys. Not Mirio; nobody told Mirio.
Katsuki and Inasa from extra classes jerked each other off one time. After that, Camie approached him. She made a very strong case that Katsuki wouldn’t know for sure if he was gay and not bi unless he had sex with a hot woman at least once, so he did it with her. It was fine. He absolutely did not cry afterwards.
Todoroki was the only one Katsuki had agreed to let top him.
Katsuki had really wanted to try bottoming; when he fucked Kaminari and Shinso and those two third year guys, who were all omegas, too, they’d seemed like they were having such a great time.
But Katsuki couldn’t let just anyone top him. It had to be someone whose strength and intelligence he could acknowledge as being on par with his own, which narrowed his options considerably.
A point in Todoroki’s favor in addition to his heroic talents was that he was not an alpha, but a beta. That meant Katsuki wouldn’t have to worry about Todoroki claiming or knotting him; Katsuki didn’t want to get chained to anyone yet, and he wasn’t willing to be put out of commission for even one day because of his fucking sexcapades, enjoyable as they may be.
The sex was pretty good considering that Katsuki had never bottomed, and Todoroki had never fucked.
Todoroki tried to kiss Katsuki while Katsuki was cumming on their stomachs and Todoroki was cumming inside him, but even then Katsuki jerked his head away; Todoroki kissed his neck instead, but the second Katsuki felt the scrape of his teeth, he shoved him violently.
“No marks, bastard! Now get the fuck outta me.”
Katsuki never let anybody kiss him, and he never hooked up with anyone more than two or three times, always with at least a month or so elapsing before he’d do it with the same guy again.
He didn’t want anybody getting attached when he was very much not interested in all that. He knew the whole no-strings thing was big part of his appeal, anyway, and it seemed like for every guy he hooked up with, three more were knocking on his door. Why lock himself down?
Katsuki didn’t even think half the dudes were all that into him, really. Just pent up from their unending grueling training, during which they were constantly surrounded by other spandex-clad teens.
For guys in the hero course who were into girls, they had almost no chance of getting down with one. The young women at UA were serious about their futures; they didn’t want to take big risks for their bodies or their reputations or even their feelings. Plus, the hero course attracted a lot of lesbians. The only girls anybody knew of at UA who were fucking were the ones in serious long-term relationships, and there weren’t that many.
So that left the only slut around: Bakugo fuckin’ Katsuki.
Katsuki didn’t really mind when he was messing around in secret with “straight” dudes; cumming is cumming, and Katsuki thought it was kinda hot to imagine that one day those guys would be old and married to women who probably wouldn’t ever find out that their husbands’ first sexual encounters were with a strapping young buck like him.
Just don’t tell Deku.
Don’t tell his friends.
Don’t let Deku find out.
—
Class 1-A’s performance in the school festival went off without a hitch. Total perfection! Izuku had stopped Gentle Criminal’s interference, and their performance made Eri smile, which was definitely a high point in Izuku’s budding hero career.
And now they were going to have a party! Momo invited everyone in class to her place to celebrate after, and they got permission to take a school bus for the occasion.
Izuku was happy the other guys had managed to rope Kacchan into coming along.
He and Kacchan had hardly spoken since their fight at Ground Beta. They’d had classes together, of course, but otherwise they’d been on separate tracks for a while.
Ever since that fight, Izuku felt like he and Kacchan were on a more level playing field, and that Kacchan begrudgingly respected him as a rival.
Kacchan was changing in other ways, too. He was getting along with their classmates; he’d agreed to play drums in the festival; he’d cooperated, however obstinately, to kill the audience with their sound.
Izuku had even heard from Todoroki that Kacchan mentored troubled kids during their supplemental classes.
Little by little, Kacchan was mellowing out and treating everyone, including Izuku, much better.
Yes, even after everything that had happened that day, Izuku still found himself daydreaming about Kacchan, grinning over how much his childhood friend had to change to be able to do all that.
But of course he could. Kacchan is amazing.
Izuku pictured Kacchan’s explosive performance on the drums that morning; he giggled, out loud, to himself, from the little bubble of joy that popped out of him at the memory.
Then Izuku paused the futile combing of his hair and frowned.
That had been happening a lot lately - daydreaming, thinking about Kacchan and giggling to himself.
Hmm.
He guessed it could be because he wasn’t really afraid of Kacchan anymore, so he could see the amazing parts of him even more clearly than usual.
He also felt like lately, when he was near Kacchan, he could smell him more clearly than usual. And even to Izuku’s underdeveloped olfactory senses, it was a very nice smell. Familiar and homey.
Izuku still couldn’t interpret body scents like his classmates, most of whom had presented before they even came to UA; Kacchan presented omega when he was just eleven.
Izuku still had no discernible scent himself, like a pup; even betas exude a calming, neutral musk.
He wasn’t the only one still unpresented in his class, though. It wasn’t a big deal.
Izuku went back to attempting to tame his hair, and he tried to think about anything but Kacchan or sex.
—-
Holy shit, Ponytail’s family was loaded. Maybe this wouldn’t completely suck.
The students entered a lavish yet comfortable parlor, full of plush chairs and elegant side tables. It had a huge TV screen with a great sound system at one end that was playing music videos.
“Oh, everyone, I’m so thrilled you could all make it. Let’s have a toast!” Momo enthused; then she clapped her hands twice.
A butler appeared, pushing a cart of bottles and flutes; Momo explained that the champagne flutes were not made of glass but an almost unbreakable substitute that she had invented herself.
Impressive. Wait. Alcohol?
Katsuki narrowed his eyes at the cart of bottles. There were a lot of bottles.
Iida balked.
“Momo, I do not think it is befitting of hero students to engage in underage drinking and -”
Momo deflated a bit at that (it’s simply not a soirée without champagne!), and the rest of the class groaned.
“Come on, man, it’s a party!”
“We’re off campus, on private property!”
“We deserve to live a little!”
“Yeah, we almost die all the time!”
The protests went on like that until Iida was harangued into submission and the flutes were filled and passed around.
Katsuki was silent, observing how the tide turned. He didn’t want to be a square like Iida, but he had a bad feeling about this.
Liquor makes loose lips, and loose lips sink ships.
Still, Katsuki downed his glass with the rest of them (exceptions being Iida and Tsu, who didn’t mind being squares).
Katsuki filled his glass up again with the rest of them, and they all settled onto the couches, chairs and loveseats with their drinks.
—-
Izuku was so excited!
His first real high school party with drinking.
It felt right, but also wrong in a fun way, after everything he’d been going through the past few months. He knew it wasn’t exactly good for his body, but… neither was stress! It was healthy to let loose once in a while, and almost everybody else was doing it, even Kacchan.
Mina piped up.
“Let’s play a drinking game!” she suggested boisterously.
“Yeah!” encouraged Mineta eagerly.
“I want to do it, even though Mineta wants to do it,” drawled Shinso, who Izuku had made sure got an invite.
“What should we play?” asked Uraraka.
“I was thinking Never Have I Ever!” Mina enthused.
“No,” said Kacchan simply, loudly.
“Yeah, let’s play something else,” Kirishima affirmed.
“Definitely,” Sero added.
“Yeah, not for me,” Shinso said.
Iida joined in.
“Yes, I know about that game, and I think it could lead to discoveries our classmates may not be comfortable with. I’m against all of this already -”
Izuku would have liked to play, but he said nothing, since Kacchan had said no so fast; Izuku did always love to learn more about his classmates.
“You guys are all so lame! Fine, let’s just play Rock, Paper, Scissors,” Mina amended. “Loser downs their flute, winner plays the next person, til we’re all drunk!”
There were a few cheers and laughs at that announcement.
—
Katsuki didn’t really want anybody getting drunk tonight, but he’d already had to shoot down one game.
They played rapid-fire, the rules ensuring that everyone would have to drink by the end of each one of their turns.
After five rounds, Tokoyami, Dark Shadow and Hagakure were laughing so hard that they couldn’t really play their match (in their defense, playing that game against - or as - a pair of floating gloves is hilarious), and they all decided that they’d played long enough.
“OK!” Mina yelled, much louder than necessary.
“And now… Spin the Bottle!”
There were a few cheers and a few groans. Katsuki just rolled his eyes.
“I’m out,” said Katsuki. “You idiots do whatcha want.”
Katsuki heard a little muttering and laughter, and then he heard something that scared him.
“Wha’dya say, Sero?” came Deku’s voice, cold and dangerous but also slurring and intoxicated - not a great combo for the user of One for All.
Oh, shit. Deku in particular maybe definitely shouldn’t have had so much to drink.
Deku was sitting right behind Sero, which Sero must not have realized in his half-stupor; he’d been whispering something to Kaminari.
—-
Sero Hanta’s heart was in his throat as soon as Midoriya addressed him.
What he’d whispered to Kaminari was, ‘That’s Baku-hoe for ya… he’ll dick ya down but never wan’sta make out.’
Hanta decided to say something false and embarrassing, rather than break the one damn rule to hooking up with Bakugo.
“Ahhh… I just told him I wanna kiss Bakugo, so I wished he would play, haha, but it was a joke, though.”
Bakugo scoffed.
Kaminari got the drift and teased, “Haha, yeah right it was a joke!” to support the ruse.
Please buy it please buy it please buy it -
Midoriya furrowed his eyebrows.
“Hmm. I thought I heard… hmm. Ok,” Midoriya said, taking another sip of champagne as he appeared to forget his train of thought.
The class didn’t end up playing Spin the Bottle. Mina got clued in eventually that she was one of the only people there who had actually kissed somebody before.
Midoriya dozed off in his seat. Hanta was hopeful that Midoriya would forget the whole thing, and that Bakugo wouldn’t murder him for his mistake.
—-
Katsuki was finally starting to relax and have fun.
Sure, everyone was drunk, and those two idiots had obviously let something slip, but Deku was drunk, too. It seemed like they’d covered for it, and the nerd probably wouldn’t remember.
For Christ’s sake, Deku had already passed out. He’d been out twenty minutes now, barely moving.
Katsuki had switched from champagne to water, so he was feeling more like himself already, but he needed to piss. Momo sent him in the right direction.
When Katsuki came back out of the bathroom he almost walked into Kirishima.
“All yours,” he huffed out, moving to go around him.
Kirishima put a hand on Katsuki’s crotch.
“Wanna go, Bakugo?” he asked with a grin, and he flexed his interested alpha scent, just a puff. Smelled like red bricks.
Katsuki smirked and pulled Kirishima back into the bathroom with him.
“Lock the fucking door,” he barked as he unbuckled his pants.
Kirishima hastily obeyed, turning the little latch on the handle.
But Kirishima was drunk. He did lock the door, for a moment; his butterfingers unlocked it again by accident before he turned to suck Katsuki’s dick.
—-
Several classmates near Izuku screeched with laughter, and the sound woke him up with a start.
Oh, he really needed some water. Oh, but first he really needed to pee.
Izuku asked Jirou to direct him to the restroom, since he knew she had been to Momo’s place before; Momo was busy trying to make a deck of cards for them to play another drinking game. It wasn’t going very well, since she couldn’t really concentrate after six glasses of champagne, and she kept producing decks full of only jacks and jokers and sevens and threes.
Izuku stumbled in the direction Jirou had pointed, and when he got to the right door, he opened it.
What he saw didn’t make any sense.
Kacchan.
Kacchan was on his knees on the tile floor, eyes closed, hands clenched into fists on his thighs.
Kirishima stood in front of Kacchan’s face with his pants down, his hips bucking, his dick thrusting in and out of Kacchan’s mouth, his hand tightly gripping Kacchan’s head by his blonde hair, his own head tilted back in pleasure, biting his lip and moaning as Kacchan sucked him, cheeks hollowed.
“K-Kacchan?” Izuku stammered out, reality crashing around him.
—-
Oh fuck fuck shit fuck WHY NOW -
As soon as Katsuki heard that nickname, his eyes popped open, he made muffled shouts, and he pulled his mouth off Kirishima, pushing the hard boy roughly away in the process.
Unfortunately, Katsuki making sounds in the back of his throat, then popping off his dick and shoving him were just what Kirishima needed to cum in Katsuki’s face, groaning.
Katsuki coughed and wiped his now-stinging eyes, barely managing to choke out the words,
“Deku -”
Cough.
“Don’t freak out -”
Cough cough.
“It’s fine!”
Hack.
Deku’s face went from dazed, watching Katsuki, to enraged, looking to Kirishima, who was still drunk and reeling from his orgasm, and who had barely registered that they had company.
“No,” Deku growled.
That’s when it all went to shit.
—-
Izuku felt like he’d exploded; like a bomb went off in his heart and turned his body into shrapnel.
Izuku thought his right arm must be on fire, and then he crashed to his knees as some kind of wild black ropes or vines or tendrils or tentacles or lightning or whips spewed out of it. They filled the room, blacking out the lights so it was no longer possible to see anything.
Izuku could vaguely hear yelling and thumping and crashing and banging all around him, but he couldn’t make sense of anything over the searing pain in his arm and the blood pounding in his ears.
At the same time, his skin was prickling everywhere, and he doubled over from the sharp pain in his gut. He vaguely registered that his dick was hard and throbbing. He could barely breathe, but when he did, each inhale reeked more and more with the distinctive smell of gasoline.
Was he being attacked by a villain’s quirk? Oh, god, where was Kacchan!?
Almost as soon as he thought of Kacchan, Izuku could hear Kacchan hollering,
“What the fuck!!”
-and then Kacchan was flung into Izuku’s free arm, wriggling and struggling but wrapped like a mummy with his hands strapped over his face in an irate impression of monkey-speak-no-evil.
The next moment, Izuku felt himself hurtling through the open bathroom window, holding onto the bundle of angry Kacchan for dear life, even as Izuku’s blood boiled under his skin and his right hand felt like it might fall off soon, based on the sensation in his arm.
Somehow Izuku’s dick was still hard, and the smell of gasoline had followed them outside.
They moved like some kind of giant spider, the whips forming spindly legs to walk them over the tops of buildings and trees for miles.
Izuku tried to focus and make whatever this stuff coming out of him was just STOP, but he seemed to have no control whatsoever.
Izuku was sweating profusely despite their speedy motion through the cold night air, and every passing moment made his skin itchier and his dick harder. At some point he pissed himself.
Izuku’s stomach growled, suddenly filled with an emptiness like he hadn’t eaten in days. He noticed the smell of katsudon in the air, and his mouth watered, and then he realized that the smell was somehow coming from Kacchan.
A sound boomed out of Izuku’s own chest that he had never made before: a deep, rumbling growl. Loud and sonorous.
With horror, it suddenly dawned on Izuku where they were going and why.
They were approaching his hometown. They were going to his house, which was empty, with his mother out of town to visit family.
And he was currently presenting as alpha and instinctively heading home to go through his first rut.
And he had taken his desired omega with him.
Kacchan.
No no no no no -
None of that explained the whips, but it seemed like whatever they were, they were following the lead of Izuku’s basest animal instincts.
Izuku howled, and he cried, and his skin burned, and his dick had to be purple by now, and it felt like knives were stabbing through his gums, and Kacchan writhed in his grip, and before long they crashed through Izuku’s bedroom window.
Thanks to the whips, they landed on the small bed, and all the broken glass was captured and thrown away.
Thanks to the whips, in less than a second Kacchan’s restraints were readjusted, so that he was lying face down on the bed, his hands secured above his head, his mouth gagged, and his legs spread wide open, ass presented.
Izuku’s heaving body was on all fours over him, looking down, his mouth dripping blood from his newly-sprung fangs onto the back of Kacchan’s neck as he panted.
Kacchan wriggled and squirmed and made pointless, muffled noises.
Izuku was burning, growling, his aching gut and swollen dick and salivating tongue and bleeding fangs calling out to him to have his way with his trapped prey.
But Kacchan was struggling to get free. He smelled livid; his scent was like burning hair now.
With every fiber of his being, Izuku hated to see Kacchan suffer, and that hatred overrode his primal desire to take Kacchan for himself then and there.
The vines had to be stopped; they were hurting Kacchan.
Without any other ideas on how to defeat them, Izuku activated One For All at twenty percent and smashed himself in the face.
Izuku was only out for a minute; the next thing he knew, he was on the floor, looking up at Kacchan who was still on the bed, now sitting up and catching his breath. He looked mad, but at least he was physically unharmed and finally liberated from the black whips, which had vanished.
“Kacchan, thank goodness, I’m so sorry-”
“Shut the fuck up,” Kacchan said in a deep, low, authoritative tone that made Izuku’s spine tingle and his lips snap shut.
“I need to fucking think for a second. Stay back, motherfucker!”
Izuku hadn’t even noticed that he’d started moving towards the bed, and he stumbled back again at Kacchan’s warning, falling and hitting his ass on the floor. The impact reverberated through his extra hard dick and made him moan out a cry of sweet agony.
“Aunghhh…”
—-
Katsuki tsk’d and furrowed his brow as he kept his eyes on Izuku’s sweaty, desperate form while he considered his options.
If he tried to run, there was a good chance Deku would follow him, with or without the vines, whether or not he wanted to. One or both of them could get badly injured, and they’d probably still wind up knotted, but in public.
They could call for an ambulance or try to get to a hospital, but given the circumstances, civilians could get hurt.
There was no denying what was happening; Deku was presenting alpha and entering his first rut, right now. On primal instinct, he’d taken Katsuki, an omega close to him, to his den, to share it.
Now Deku’s mouth was bleeding from where his huge new fangs had pushed out and replaced his canine teeth.
Deku’s gasoline smell was growing stronger within the confines of his bedroom, even with the window broken open, and it was making Katsuki feel pleasantly light-headed already.
Deku’s hard-on was really obvious, as was the intense restraint and concentration with which he was holding himself back; he used those shiny new fangs to dig holes into the meat of his already-gnarled hand, mumbling into the bites as he waited with the patience of a saint for Katsuki to speak again.
Katsuki sighed. Finally he said,
“I guess you’re gonna have to knot me.”
Deku made a sound that was like a moan but tortured, painful, and he didn’t move. He just bit more firmly into his hand and started shaking harder.
Katsuki ran a hand down his face and took a deep breath.
This wasn’t how he’d expected to take a knot for the first time, all… by surprise and under ridiculous circumstances… with Deku.
Deku.
He’d thought about it, of course.
He’d just never once considered it as a real possibility. He’d treated Deku so badly for so long. Yet here the nerd was, fucking presenting and getting a new quirk or some shit just from seeing Katsuki with somebody else.
Well. With another alpha.
Deku quivered on his bedroom floor, dripping blood, exerting every ounce of his iron will to keep from pouncing on Katsuki.
It was actually... pretty hot.
“Shit, Deku, it’s… fine. I’m… into it. C’mon, it’ll be…” he rolled his eyes and finished, “…fun.”
—-
Spoken by Kacchan to Izuku in that moment, his hesitant allowance might as well have been instead, ‘Please fuck me hard right now, Daddy, pretty please.’
So that’s more-or-less what Izuku heard.
His green eyes went black, and he pulled his fangs out of his fist.
He exploded with scent, and his rut began in earnest.
He was on top of Kacchan in an instant, and then he didn’t really know what he was doing anymore.
For Izuku, as soon as their bodies were sharing heat, it was like he’d been dropped in a giant bowl of hot katsudon. Everything everywhere all around him was warm, and soft, and smelled good, and tasted good, and felt good, and the serving size was just as unlimited as his appetite.
Kacchan for dinner.
—-
The experience was a little bit different on Katsuki’s end, since he was the one being eaten alive.
“Ow, fuck, Deku, let up, slow down -” Katsuki complained, but it seemed like Deku couldn't hear him anymore.
Shit.
In seconds, all their clothes were torn and on the floor.
By the time he was naked, Katsuki had inhaled enough of Deku’s possessive, horny gasoline smell to render his omega pliant for the alpha; if he hadn’t, he’d probably have reconsidered his decision to stay.
Deku was all over him, almost a blur as he moved around Katsuki’s body with some obvious help from his quirk, so he looked like a freaky movie monster; it was like he was trying to touch every part of Katsuki at once.
And he wasn’t just touching. He was mouthing, licking, sucking, taking bites.
Bites, sharp and hard, one after another, followed by the firm press of tongue, just, everywhere - hip to pit, pit to fingertip, crotch to toe and then again on the other side. Methodical, like the alpha had been presented with a whole roast chicken and wanted to clean every bit of meat off the bones.
It should have hurt; it should have hurt a lot. Deku was leaving holes and cuts and bruises all over Katsuki; he was drinking his fucking blood.
But Deku’s scent made being consumed by him a pleasure; each bite made Katsuki’s cock harder, his hole wetter, his pleasure more intense.
Katsuki came.
His scent bloomed out.
Deku sniffed and whined, and then he flipped Katsuki over, easy as a rag doll, and was behind him in a second. Deku grabbed Katsuki’s hips in both hands and shoved his dick forward gracelessly, humping up against Katsuki’s slick ass without penetrating it a dozen times before his head caught, and he pushed the whole thing in at once.
They both cried out.
—-
Izuku didn’t exactly understand that he was losing his virginity to Kacchan at that moment.
He was just in outer space, meeting god.
—-
“Bastard!” Katsuki yelled ineffectually as Deku absolutely pounded him.
Smack-smack-smack-smack-smack-smack-smack-
The fucker was definitely using his quirk; nobody’s hips could snap that fast on their own.
And fuck if he wasn’t thick. Deku’s length felt on par with Katsuki’s own, but gun to his head Katsuki would guess its circumference was double.
“Deku, slow the FUCK down!” Katsuki implored, craning his neck to look behind him when he got no response.
Deku looked like a crazed animal. He was staring with blank black eyes at his own member slamming in and out of Katsuki, and his jaw was open slack, tongue lolling out, drooling, fingers clawing into Katsuki’s hips so hard they drew blood.
So, yeah, Deku wasn’t listening.
Katsuki rested his head back down, braced himself as much as he could, and took what he was served.
“Nnnnnpffffff…”
Slam-slam-slam-slam-slam-slam-slam-
“Augh... god... dammit... ah-”
Finally, Katsuki felt Deku's knot expanding, even as Deku continued shoving in and out, in and out, in and out, pulling and pushing the expanding bulb, punishing Katsuki’s hole more with every thrust.
Finally, it held; Deku pulled achingly, violently hard to thrust back out again, but he could not.
Deku collapsed, heavy on top of Katsuki, opting to grind their knotted pelvises against the mattress, using the omega’s hole roughly until he came, and came, and came inside of it.
The friction of Katsuki’s dick against the bed, the massage on his prostate and the wet heat filling him up inside - they overtook Katsuki, and he came on the sheets beneath him.
—-
God told Izuku to go through the door.
The door was very familiar and yet absolutely unlike anything Izuku had ever known. Something about it made him uneasy, but god practically pushed him through it, anyway.
—-
Deku’s knot rocked aftershock after aftershock out of Katsuki’s stretched and beaten hole.
And then Deku’s hands were on Katsuki’s shoulders, and Katsuki was held down by the strong, smelly alpha behind him, and his body knew what was about to happen, and there was no fight left in the omega; quite the opposite.
Katsuki tilted his head to one side.
Deku growled, and his fangs pierced deep into Katsuki’s scent glands with pinpoint accuracy.
“Aah! D-d-deku…”
Katsuki whimpered.
A minute later Katsuki felt a moment's relief when Deku pulled back, releasing his throat from his fangs.
Relief was replaced by shock when Deku pushed Katsuki’s head to tilt in the opposite direction.
Deku bit down and claimed Katsuki in his scent glands on the other side, too.
“The fuuuuu…”
Katsuki tried to complain, because what in the actual fuck, but Deku was circling their knotted hips and doing his best to suckle at the second bite with his fangs still lodged deep in it. He used his hand to squeeze the meat around the first bite, urging out blood and oil like he was popping a zit.
It all felt painful and strange and warm and good and right.
They both came again, and just as Katsuki started to think that if he got any fuller inside he’d literally burst, Deku’s knot finally receded, spilling fluids all over them.
—-
The door had led straight to the Garden of Eden.
Izuku was naked. Kacchan was there, also naked.
Kacchan reached out and handed Izuku a blood red apple, so Izuku took a bite. It was bursting with the most arousing flavors, so he took another bite.
They kissed and rubbed against each other; they fucked with the knowledge that made it a sin.
Then god threw them out of the Garden.
Izuku felt like he fell ten stories to land in his body again with a thud.
—-
“Ah! What! Omigod - Kacchan!”
Deku was back, apparently. The nerd pulled out, releasing a little “Ungh!” when copious cum and slick poured out, and then he ran to turn on his bedroom light.
Katsuki just sighed. This part had come faster than expected, but presentation ruts are famously short, and apparently shorter still with an omega to knot.
With the light on, Deku could see the damage, and he was immediately on his knees on the floor next to Katsuki, obviously wanting to reach out to comfort him but fearing that his touch would be unwelcome.
Katsuki was pillowing his head on his arms, naked, covered in bite marks and bruises from head to toe, bleeding everywhere, smelling of katsudon and gasoline, eyes drooping and blissed out, and claimed on both sides of his neck.
Voice wavering with unshed tears, Deku stuttered,
“K-kacchan, I’m so - I’m so sorry, Kacchan, I never thought -”
Katsuki, sore but not defeated, propped himself up and interrupted,
“What, that all you got? You gonna cry now?”
Deku looked at Katsuki with big, watery eyes.
“Wh-what?”
“Told you before, asshole, it’s fine. And that was the shortest fucking rut ever, anyway.”
“Kacchan… I- I claimed you,” said Deku, tears falling down his cheeks at last.
“Yeah, twice, fuckin’ lunatic. Jesus.”
“Wh-what are we going to do?”
“Pff... Shower, get dressed, and then go back to school and see the damn nurse.”
—-
They showered separately. Kacchan tried to hide how stiff and sore he was when he moved.
They had to put on clothes that were too small for both of them - old stuff Izuku hadn’t brought with him in the move to the dorms. He thought Kacchan looked incredibly cute covered in bite marks, with his muscles bulging in tight shorts and an All Might tank, but Izuku wasn’t about to push his luck right now by mentioning that.
Kacchan was acting sort of… fine… with everything? That couldn’t be right; he must be putting on a tough front.
“K-kacchan?” Izuku stammered after they tied on some of Izuku’s old shoes by the door.
“What, dipshit?”
“A-are you ok?”
“The fuck - I guess.”
“What are we gonna tell people?”
Kacchan scoffed.
“Seriously? Our scents will tell them everything, Deku. There’s no hiding this.”
“Oh. Right,” said Izuku, embarrassed. God, he was such a noob alpha.
And yet he’d already claimed his omega. But he hadn’t…
“W-well th-then, uh, K-kacchan, um, well-”
“Spit it out, nerd!”
“WillyoubemyboyfriendKacchan?”
Kacchan rolled his eyes and sighed and shrugged.
“Fuckin’… it’ll be harder not to be, now.”
Taking that for the affirmation it was, Izuku smiled and asked quietly,
“Then… can I kiss you?”
—-
Katsuki scowled.
He reached out to pull Deku close and initiate the kiss himself; he smashed their soft lips together.
Deku moaned, high-pitched like a girl, and he threw his arms around Katsuki’s neck as Katsuki moved his mouth against him and deepened the kiss. They both groped inexpertly with their tongues, holding each other close and frenching, wet and desperate, in the doorway.
Katsuki finally pulled away, chuckling a little at the whole fucking thing.
His first kiss.
Deku smiled at him shyly.
“C’mon, let’s get back already,” Katsuki said, and with a little “Right!” from Deku, they did just that, blasting through the night air towards UA.
—-
Kacchan didn’t want to talk much after. They walked back to the dorms in silence after Kacchan got the worst of his injuries healed (it killed Izuku that he’d hurt him so badly that many of the bite marks and bruises remained, after treatment, in addition to the furious claiming bites).
Waiting for the elevator, Kacchan said,
“It’s ok if it’s you.”
Izuku’s breath stopped, and he tried to hide that he was tearing up again.
“Kacchan…”
When they got in the elevator, Kacchan let Izuku kiss him, before pushing him off on the second floor.
Half an hour later, Kacchan came to his door, scowling and unable to sleep.
They cuddled; they slept.
—-
The first day back in classes was awkward.
Like Kacchan had predicted, everybody seemed to understand exactly what had happened without a word of explanation, even with Kacchan’s shirt buttoned and his tie tied conspicuously appropriately to hide the double bite that reflected rather poorly on Izuku.
Oof. He knew the marks would heal and become more discreet with some time, and that made him... angry. Honestly, he wanted people to know that Kacchan’s boyfriend was possessive and not to be crossed.
The pair were met with blushes and muttering and snickering and wolf whistles when they arrived at home room together.
Izuku wouldn’t say it, because Kacchan was obviously annoyed and possibly embarrassed, but he found the reactions deeply gratifying.
Everybody knew that he’d claimed and knotted Kacchan, and that was just exactly how Izuku wanted it.
—-
Izuku got held up talking to All Might after lunch, so he was a little late arriving at the locker room to get ready for training.
He heard his name, so he stopped to eavesdrop right outside the door.
“Wow… Midoriya must really be a sadist to do you like that, Bakugo,” Mineta observed, obviously seeing Kacchan’s newly marked body for the first time as they prepared for training.
Izuku felt a painful sting of guilt. Was his inner alpha a sadist?
“Fuck off, Blue Balls. This shit’s normal rut stuff.”
Was that true? Izuku would have to look that up later.
“Yeah, but… he claimed you twice? Who does that? You weren’t even dating,” Kaminari mouthed off.
“Whatever, the nerd’s insane. And we’re dating now,” Kacchan mumbled.
“Gotta say, I’m kinda jealous. Happy I was your last hurrah before getting claimed, though!” Kirishima said with good humor.
Izuku didn’t love that comment, but he took deep, slow breaths and kept listening.
Kacchan growled as a few of the other guys laughed. He warned,
“Wouldn’t bring that shit up if I were you. My alpha is kinda possessive, if you couldn’t fucking tell.”
“Oh, c’mon,” Sero cajoled. “You guys practically eloped. We’re still mourning the death of Baku-hoe Slut-ski.”
Izuku saw red.
—-
That particular nickname wasn’t Katsuki’s favorite, but it was just a joke. Sero had said it in front of Katsuki before, and Katsuki hadn’t attacked him.
But if Sero hadn’t been surrounded by other capable hero students with lightning-quick reflexes, he would have died the next moment with Deku’s foot on his neck.
A scuffle ensued, and Katsuki was finally able to bring Deku back to his senses by holding him down and releasing an embarrassing volume of his calming omega scent.
“Oh, oh my gosh! Sero, Kacchan, everyone, I’m so sorry, I clearly need to work on my control.”
Deku approached Sero, who was coughing a bit and standing with Kaminari and Mineta.
“Sero, I’m so sorry I hurt you-”
“No,” Sero interrupted. “Bakugo literally just warned us - you’re not used to being alpha yet. I’m sorry. Won’t happen again, Midoriya.”
Deku looked relieved.
“That means a lot, Sero, thank you!”
Sero reached out a hand to shake, but Kaminari shoved him forward a little.
“Awww… hug it out, guys!” he encouraged.
Deku and Sero reacted jovially enough, coming together for a kind of spartan bro hug and patting each other on the backs.
Then it looked like Deku pulled Sero in closer to whisper something, and Sero froze.
—-
Izuku whispered,
“Spread the word, asshole. Anyone disrespects my omega from this point forward, they die. And I don’t mean it like when Kacchan says it. I mean, you’ll get in an accident or disappear and nobody will ever even suspect me. Got it?”
Izuku released his classmate and looked at him appraisingly.
Sero looked like he got it; he nodded, face pale and lips parted.
Izuku’s voice returned to its normal volume.
“Great. I’m so sorry again, Sero, really. Let’s do our best in training today!”
—-
On the way to training, Izuku tried to hold Kacchan’s gloved hand, but Kacchan shoved him off.
That was ok.
Kacchan was his now, and everybody knew it.
And Izuku would do whatever it took to make sure that if anyone ever looked at his omega sideways, they’d get smacked upside the head and chided,
Don’t cross Deku.