Kiribaku Oneshots

Concept 11 - New and Different

Is the kitsune chapter my only monster fucker chapter? This won't do. Let's see if I can make another one.
CW: teratophilia, siren!Kiritop, siren!Bakubottom, two dicks, very sharp teeth, tentacles?, intersex genitalia

Exposition: Based off of a concept/rp my friend and I have. Essentially, Bakugou was a pirate and he willingly got turned into a siren to stay with Kiri. So he's kinda new at the fish anatomy stuff.

It was odd at first, making out underwater, that is, but Bakugou took to it like everything he did. He got used to water in his lungs, so he had to get used to what seemed like an otherworldly sensation. He felt like he was floating, despite being curled together with his love at the bottom of their shared underwater cave, nestled surprisingly comfortably among rock and sand and seaweed. Kirishima had spent all day making this "mating bed," and he clearly knew what he was doing. Even though the sensation was new, it was still satisfying to feel their lips and tongues melt together, hands roaming as they slowly familiarized themselves with each other, tails curled together to keep from drifting apart. It's so intimate and lovely that Bakugou almost doesn't notice when something soft, but dense rubs against him. He knows the sensation. He ain't a virgin. Soon, he feels himself interacting with the sensation, both of them moaning softly into their kisses as they grind together. It feels different this time, obviously, and his curiosity is enough to make him pull back and peek down at...four? He double takes, eyes blowing wide. Yeah, there's four. Two on each of them, one on top of the other. The one on top, he had seen before when mastering the ritual of pissing like a fish. It was a bit smaller than his dick had been before his transformation, soft but inflexible with a dull point. The one below it, he had never noticed; it was long and thick, a little bigger than he was before, but not hard like a human boner. More like a tentacle, flexing and squirming as it seemingly searched for friction. His eyes flicked from his own arousal to-...holy shit. Kirishima's were so much bigger; the tentacle looked almost as long as his forearm and the base looked as thick as his wrist, if not bigger, while the slightly smaller of the two looked as big around as the neck of a bottle and was ribbed for good measure, getting wider at the base where it met his sheath.

The blonde was so shocked and mesmerized that he didn't notice his partner calling his name.
"Katsuki? Katsuki!" the redhead's voice finally snapped him out of it.
"Huh? What?"
"Are you alright? You just froze up and were staring. Is something wrong?" The blonde takes a moment to gather his thoughts, a furious blush tinting his scale speckled cheeks.
"'M fine, just...didn't know there were two," he admits.
"Oh. Did I not tell you that? Yeah, we have two," he begins to explain, backing off a bit so he can see better. He points to the smaller appendage. "This one's for liquid excrement. I believe humans call it piss," He grips the base of the larger, mesmerizing the blonde once again as it curls around his thumb before he strokes up, straightening it out to show its length. Fuck, that shouldn't have been as sexy as it was. "And this one is for breeding. It only comes out when we're aroused, which is probably why you haven't seen it until now. Both can be used when mating, but it might be safer to just use one for now-" he elaborates, bringing a hand down and using two fingers to trace the opening of Bakugou's cloaca, ever so gently spreading it open, making a shiver crawl up his spine. The blonde hisses through his teeth at the touch, barely keeping a moan behind them. "-since you aren't quite used to our kind of mating, even though this space is quite flexible." The blonde stared at his partner's crotch, salivating at the sight of those monsters. Slowly, he nods.
"Yeah, you're probably right," he agrees, but in his mind, he makes a promise to himself. 'I will fit both of them inside me.'

For now, though, he gets an idea. He tightens the grip of his tail and turns them around, pressing his love into the mating bed. "Do sirens do oral?~" He smirks down at his partner as his cheeks flush and eyes widen.
"Y-yeah, we do, sometimes," Kirishima explains, flustered by the realization of what's about to happen. Bakugou swipes his tongue across his newly sharpened teeth in a feral grin.
"Well," he starts, uncurling their tails in favor of slipping down until he can lay chest first on his partner's tail, face inches away from his squirming arousal. He wraps his hand around the base, marveling at how his fingers can't even reach each other thanks to the sheer width of the organism. He slowly strokes up, watching keenly as the appendage curls around his fingers. "Humans do it a lot, and I've been told-" He licks an experimental stripe up the length of the tentacle, drawing a breathless moan from the redhead's throat. "-that I'm quite good at it.~" He peeks back up, grinning at the absolutely ruined look on Kirishima's face. He chuckles a bit, giving another experimental stroke. "Shall I continue?~" Kirishima nods, almost lost for words before sighing an eager 'please.' Bakugou gets right to work, laving his tongue over his cloaca before painting stripes of saliva up the length of his dick, relishing in the beautiful moans Kirishima practically sings into the space of their cave, purring and crooning praises.

Kirishima watches keenly as his mate tastes every inch of him, mesmerized by the glide of his tongue...but he is soon snapped out of it when Bakugou cradles the tip of his cock on his tongue before letting the muscle slip into his mouth, covering his teeth with his lips. His eyes blow wide in nervous realization.
"K-Katsuki what are you- oh gods!~" His protest was cut off by a guttural moan as half of his dick sank into his mate's throat. He's never felt something like this, and when Bakugou swallows, sinking further down until the tip of his cock tickles against the back of his throat, he sees stars. His back arches, muscles seizing up as his claws dig into the mating bed for purchase. He bears his teeth in an almost feral groan, cursing in his Atlantian tongue as he cums long and hard down his mate's throat. It has a thinner consistency than Bakugou first thought it would, almost like drinking milk or cream, rather than the thick stickiness he's used to, but that doesn't stop him from gulping down as much as he can before Kirishima finally collapses in the bed, panting like a dog in attempt to catch his breath. His dick seems to follow suit, shrinking back into its sheath a fraction of the way, like how a human dick would go soft and shrink back into its foreskin, but just enough to let the blonde know that he just needed to get his bearings. He peers up at Kirishima, slinking up so they were chest to chest, face to face.
"You alright, Red?" he teases with a chuckle, refraining from making fun of how fast he came.

Kirishima nods, raising a hand and placing it weakly atop the small of his mate's back. He trills something in Atlantian, still clearly discombobulated from the new sensation and quick orgasm. Bakugou snorts.
"Common tongue, Ei," he requests, having only learned a few words in the language. The redhead huffs out a laugh.
"When I said we sometimes perform oral, I didn't think you'd do that," he sighs, speaking between breaths. "We definitely don't do that as much as humans apparently do...because of our teeth."
"Ah," Bakugou muses. "So that's why you came so quick.~"
"Oh hush," Kirishima snorts. "You'll have to teach me how to do that next time, but for now..." He flips them so that Bakugou is laying on his back, while he rests on his side. He drags his palm along black and orange scales, dancing around the blonde's neglected arousal as his lips find the juncture between his neck and his shoulder. "Allow me to return the favor.~" This is going to be fun.

Aaaaaand scene. Sorry I've been kinda dead! College has been kicking my ass, but I'm doing ok! Hope you guys enjoyed this one!