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Interning with Mirko is probably in the top ten worst decisions Katsuki has ever made. Sure, she’s strong, and deserves her spot in the top five but - fuck, she’s such a typical fucking Alpha. Always convinced she knows better than him, what bullshit .
If Katsuki had the choice, he would have gone with Jeanist again - but after the war, Jeanist retired, so that wasn’t an option anymore. Katsuki had internship offers from every agency in the country, but he’d chosen Mirko. A large part of him didn’t know why. A small part of him did, but he didn’t like to acknowledge that.
“C’mon, brat! Time for round two,” Mirko calls, throwing her empty water bottle into the trash can across the room - showoff - and bounding back up to him. She stretches her arm across her chest and Katsuki struggles not to stare as muscles bulge. “Unless your little omega muscles are sore, of course.”
“Fuck off,” he growls, “I can take you any day of the fuckin’ week, bunny.”
“Hah! Sure you can.” She crouches as if getting ready to leap, and Katsuki has sparred with her enough to know that means to get out of the fucking way. He jumps to the side just in time for her flying kick to miss him. While her back is to him, he aims his palm and strikes.
The light of his explosion momentarily blinds him, which is how he misses it when Mirko jumps over his head and tackles him from behind. Katsuki curses loudly, trying to reach behind to blow her off only to have his hands pinned to the ground. Mirko laughs lowly in his ear.
“Is that all you got, Omega?” She says, “C’mon, I thought the big bad hero was gonna kick my ass? Or, no, that’s not what you said - I thought you could take me ?”
Mirko’s hips grind down, rubbing against his ass, and all of the breath leaves his lungs. This, this is why he accepted her internship - as much as he hates to fucking admit it. “Fuck you.”
“No, fucking you is what I’m gonna do,” she replies, because she’s a corny bitch like that. “You’re so desperate for it, y’know? Never seen a more obvious slut. Asking to spar when you really want my cock.”
Katsuki hisses. He can feel the outline of it rubbing against him. There’s barely any cloth between them, Katsuki wearing thin basketball shorts (with nothing underneath, ‘cause, yeah, he is a slut) and Mirko in short leggings that are basically booty shorts. Maybe they’re both kinda obvious.
“Get off me,” Katsuki says, voice muffled against the mat. He gets his palms flat against the ground and detonates, sending them both flying. He’s quick to turn and face her, because a little explosion like that isn’t enough to stop Mirko.
He’s right. By the time Katsuki has turned around, she’s already got her fist flying towards his face. Katsuki barely manages to dodge it. He grabs her wrist and sends her over his shoulder, using an explosion to send her even farther than his raw strength could - which isn’t very far, ‘cause she’s made purely of muscle and spite.
“Is that all you got?” Katsuki calls. She looks up at him with a feral grin.
“Not even close.”
The spar goes on for another ten, fifteen minutes - she kicks him into a wall, he singes the hair off her arms - before Mirko manages to pin him again. This time, she grabs him by his nape and slams him into the floor.
Normally, someone grabbing his nape makes him feral. Katsuki has nearly killed alphas just for the attempt; but there’s something about Mirko that satisfies the little voice in his head, the one that calls for a big, strong alpha to force him down and make him take it.
When Mirko grabs him by the nape like that, he’s helpless to do anything but submit . He moans weakly - a mortifying sound - and a moment later the acrid scent of Omega piss fills the air. Mirko laughs at him.
“You’re so easy.” She squeezes his nape and his whole body shudders.
“Fucking… fuck off,” Katsuki replies, voice high and reedy. He taps the floor and Mirko releases his nape, allowing the wave of submissive hormones flooding his brain to recede. Mirko doesn’t move though, staying perched on his ass like she belongs there.
Mirko hums, hands trailing down the bare skin of his back, caressing it almost lovingly. “What? You want me to stop, huh?”
Fucker. She knows that’s the last thing he wants. “Want you to get fucking on with it.”
“On with what, Omega?” She asks.
Katsuki struggles not to moan at the call to his dynamic. “You fuckin’ know what.”
“Nah. You gotta say it.”
“Fuck you!” He snaps, for the fourth time within the hour. Katsuki takes a deep breath. He hates this part, hates when she makes him beg for it, wishes she would just fucking force him down and make him take it. “Stick your dick in me, or whatever the fuck.”
“What a way with words my Omega has,” Mirko purrs, voice low, and this time Katsuki can’t hold back the moan. Her words repeat in his head - my omega, my omega, my omega . The weight on his back leaves, and a whine of disappointment leaves his chest. Mirko laughs at him and says, “Show me how bad you want it.”
Katsuki looks over his shoulder at her. Her cock is straining against the fabric of her tights, fat and long and leaking so much it’s staining. Katsuki’s legs feel weak just looking at it. “The fuck?”
“ Present for me, Omega .” Her alpha voice reverberates in his ears, and once again it works on Katsuki when no other alpha’s does. He scrambles onto his knees, tugs off his shorts, and arches his back until his chest is scraping the floor. Katsuki can hear his heartbeat in his ears, waiting for his Alpha’s approval.
A hand ghosts his ass, then cracks down with a sharp smack ! Katsuki cries out, hips jerking away. Mirko’s other hand - the metal one - comes to grip his ass and hold him still. A barrage of smacks rains down, leaving burning flesh in their wake.
“Alpha,” he groans, “Alpha, fuck!”
Mirko stops for a moment. Katsuki can see her in his mind, hand stopped midair while she waits. “You gonna be good for me, Omega?”
Katsuki nods into the ground and gets another slap for it. “Damnit! Fuck, yes, I’ll be good!”
“That’s what I thought.” Mirko’s hands pull away - Katsuki assumes to get herself undressed, because a moment later the spongy head of her cock is pressing into the lips of his pussy. He’s soaking wet, slick and piss dripping from his folds. She stays there for a moment, just rubbing her cock back and forth, see-sawing between his clit and his hole.
It’s just when he’s getting impatient that Mirko finally breaches him. Even after the dozens of times they’ve done this, Katsuki can’t get used to how big she is. It feels like she’s splitting him open, carving space for herself within his body. The thought has Katsuki bearing down, so close to orgasm that he can’t help it.
She slaps his ass again. “Be a good bitch and loosen up for me.”
Katsuki desperately wants to be a good bitch, but it’s so fucking hard.
“‘S too big,” he whines, voice shaking. “Can’t.”
“Of course you can, you were fucking made for it.” Mirko slaps his other cheek. “Don’t you wanna be good for me, Katsuki?”
“Wanna,” Katsuki gasps, “Wanna be good.”
A hand slips around his front to rub against his clit. “You wanna be my good bitch? Say it, say you wanna be my good bitch.”
“Wanna - wanna be your good bitch, Alpha,” he says, “c’mon, Alpha, give it to me-”
Mirko slides in deeper, then all the way, the wet lips of her own cunt pressing against his. Katsuki cries out - she gets so deep , cock rubbing against parts of his pussy that not even the best toys can. He’s tried to replace it, tried to find toys that can replicate her but - nothing can.
“Perfect Omega,” she says, voice tense. “Fuck, so goddamn tight , so wet - if the fucking chart considered how perfect your pussy was, you’d be number one in no time. Well - number two. Behind me.”
“You’re so fucking annoying,” Katsuki replies. He rocks back, desperate to be fucked. “Jus’ do it already, you fucking-”
The term ‘fucking like rabbits’ exists for a reason. Mirko has the stroke game of a God . She fucks him just right, not too hard or too fast - just. Fucking perfect, pounding into his sweet spot over and over again but not too much, not enough to hurt. Her fingers haven’t left his cock, rubbing it viciously while she fucks him.
“Gonna cum,” he rasps, “Gonna - Alpha, gonna - please , fuck, don’ stop, so fuckin’ close-”
“Come on, Omega, be a good bitch and cum on my cock. Gotta get you nice and loose for my fat knot,” she says. Katsuki is helpless but to obey, cumming hard enough to see stars. Mirko doesn’t stop, she keeps going, even after his orgasm has waned and he’s become so sensitive it hurts.
“Alpha.” His voice barely works, syllables slurring together.
Mirko’s rhythm suddenly changes. Her knot has started to grow, and she buries herself in deep, grinding slowly in and out of Katsuki. She holds him on the fattest part, then shoves herself in, the drags back out to do it all over again. It leaves his nerves shredded, unable to take it anymore.
“Can’t, Alpha, I can’t - can’t take it, fuck-”
“Sure you can.” Mirko sounds breathless, now. She must be close to cumming. If the size of her knot is any indication, she’s practically there already. “You’re the strongest, right? You can take it, Omega.”
“Can’t,” Katsuki says back, and fuck - normally, he’d be mortified at how he’s acting. But Mirko always leaves him like this, cock drunk and stupid. “Can’t, ‘s too much-”
A hand clasps over his nape, and all of it - the paid, the oversensitivity, the doubt - washes away. Katsuki gasps, then groans, relaxing into it. Distantly, he hears the wet splash of piss hitting the floor. He feels Mirko’s knot sink in, and a moment later, she’s spilling inside of him. Hot alpha cum fills his cunt, and it feels so good it has him cumming again.
“Fuck, that’s right,” Mirko groans in his ear, “Milk my fuckin’ knot, bitch.”
“Alpha,” he whimpers. Mirko shushes him, squeezes his nape again so he shuts up. Her knot is still rubbing into his g-spot, but he knows she won’t move no matter how much he begs, so he doesn’t bother. Katsuki will probably cum two or three more times before her knot goes down - and that’s just if she doesn’t get a second wind. He’s in for a long night and sore knees, but at least his classmates will be thankful when he comes home soft and sated.
Katsuki knows why he took this internship - it’s just kind of embarrassing that everyone else does, too.