The pact was never supposed to be something Izuku had to follow through on.
It was bro code. Dumb shit you promise each other at sleepovers and never expect to come due. Like, yeah, in a world of Quirks, was getting randomly hit by one that changed your biological sex possible? Yes. Was it likely? No.
Did Izuku ever think that he'd actually have to let the others hit if he one day turned into a girl?
Absolutely not.
But, here he is. No dick left to his name, tits on his chest, a very special place between his legs that his classmates would love to take for a spin, and Kaminari kneeled right in front of it, very ready and willing to do exactly that.
Maybe he should have told Kaminari he didn't mean it when he said he'd let him ride.
It's kind of a hard sell, albeit, now that he's let Kaminari suck on his tits for half an hour. Sure, he motorboated him in a bro kind of way, but a fuck? They're not that good of bros.
Kaminari furiously pumps his exposed dick with a slick handful of lube and stares dead at Izuku's naked tits.
Izuku considers, again, backing out of the pact.
He agreed with the rest of the guys at two in the morning during an ill-advised movie marathon, and he guarantees that not a single one of them ever thought it would actually happen. Kirishima put on some cheesy film from ten years ago where a hot-headed, misogynistic baseball star ended up turning into a woman from a freak Quirk accident. He kept coming to work like normal--cue half of his team getting hot and bothered by his body's new assets, and the main character discovering the discomfort of womanhood.
Sero insists that bro code means letting your bros hit when you've got a limited-time unrestricted access to a cunt, and next thing he knows, Izuku's promising with the rest of them to let the guys in his class to take him for a ride if he ever ends up stuck in a girl's body.
He didn't think about it.
It wasn't supposed to happen.
Then, he gets bumped into by a random kid while crossing the street, and the next day, Kaminari's at his door with a red face and a bottle of lube.
Kaminari briefly stops jerking himself off. "Midoriya, dude, I just want you to know that you're the coolest guy I have ever met. Thanks for letting me do this."
And by that, he means fuck him.
It'd be objectively insane to actually go through with this. Izuku's already let him suck on his tits. He's let this go way further than anyone ever would.
"It's just"--Kaminari blushes a bit--"I've never done this, like, with someone before. And it's kinda intimidating to have to figure it out when you're trying to impress a girl. It's sort of a big relief to get to do it with a bro, you know?" Immediately, he tries to correct. "Not like, with a bro, with a bro, because that'd be gay, but like. With a bro with tits. You know what I mean."
Izuku unfortunately does.
He… he should let Kaminari go through with it, right? He did promise. And he likes to help his friends.
Probably no one else will ask him, anyway.
"It's fine." His own voice still freaks him out with how high it is. He lays back against his pillows so he won't have to look at Kaminari's dick anymore. "Just… do it when you're ready."
"Oh my God," breathes Kaminari. He quickly scoots closer, grabbing Izuku's hips with both hands and hoisting him up abruptly.
Izuku grabs onto the bed sheets to steady himself.
Kaminari releases his right hand so he can fumble for his dick. Clumsily, he lines himself up with Izuku's entrance and starts to press.
Izuku screws his eyes shut.
"This is the best day of my life," whispers Kaminari, and he eases his cock in.
Izuku grabs onto Kaminari's shoulders with both hands.
Kaminari didn't seem that big when Izuku first saw him. His own dick had been bigger, back when he still had it.
Of course, he didn't quite consider how small vaginas were. After Kaminari was done rubbing his face over Izuku's tits, Izuku had tried to scissor himself open, but he might as well have done nothing for all it helps. It feels like Kaminari's trying to thread a needle with a pipe.
"Do you want me to stop?" says Kaminari, not stopping. He hurriedly shoves himself a half inch deeper, as if he's afraid that's as far as he'll get to go. It sends a spark of pain up Izuku's spine.
Izuku grits his teeth and forces his legs wider. That'll just make this take longer. "No. It's fine. Keep going."
Kaminari nods distractedly, eyes glued to where his cock disappears into Izuku's body. Then, he grabs Izuku's hips with both hands and jerks his body down hard on his dick.
The only reason why Izuku doesn't scream is because he regularly shatters his own limbs.
"Kaminari," he groans, throwing his head back.
"Does that feel good?" demands Kaminari. He pulls out an inch, then shoves back into him roughly. "Did you just come?"
No and no.
"Go slower when you're with a girl next time." Izuku tries to rock with him, but he can't meet the uneven speed of Kaminari's short, shallow thrusts. Eventually, he realizes it's just easier to lie there and let Kaminari use him like a hole. "You'll hurt them."
He can't tell if Kaminari even hears him. His jerking becomes sloppier. Izuku rocks unevenly backwards into his pillows, feeling like a cheap toy. "You're so, so fucking tight. And wet."
Not from Izuku's perspective. He's not nearly wet enough for Kaminari's dick to slip through him easily. It's dry and slightly painful, and Izuku finds himself gritting his teeth.
He manages three more clumsy, uneven thrusts before he dumps his load right inside of Izuku. Then, he immediately collapses on top of him, face pressed into the crook of Izuku's neck, panting wetly against his skin. His cock starts to slowly soften inside of Izuku, something hot and wet spreading uncomfortably through him.
That was… anticlimactic. And not very pleasant.
God, he feels terrible for girls. Is this what it's like for all of them?
Izuku decides to give Kaminari a minute before kicking him out of his room.
This is too generous. Kaminari's breathing evens out almost immediately, and he falls asleep with his dick still stuffed inside of Izuku.
He probably should have told him to get lost.