Chapter Text
Physically, Kiyoomi is a strong alpha. He boasts thick biceps and muscular thighs, hits a volleyball as if he’s trying to burn a hole through the floor, and had no issue pushing his beta teammate's car up a steep hill when it suddenly died on them. Kiyoomi is a strong alpha, but his resolve is weak when it comes to omegas in heat. Specifically, unfortunately, regrettably, young omegas in heat.
Kiyoomi will be the first to admit that he is a bit fucked up. His fantasies are filled with taboos, things he could get arrested for if he ever acted upon them. His dreams show him little girl omegas choking on his knot and young boys presenting their leaking pussys until Kiyoomi wakes up covered in sweat with a raging boner.
He has somehow refrained from acting upon his urges for 26 years, watching and reading illegal porn to keep himself reigned in. Kiyoomi’s indulged in other taboo acts. The kind of things that are slightly less illegal and don’t taunt him with as much guilt. He has stayed away from underage omegas for his whole life despite his constant urge to ruin their innocence, but Kiyoomi knows that his restraint is a ticking time bomb.
A time bomb that finally goes off when he leaves for an unassuming walk to the grocery store.
Kiyoomi is less than three minutes into his walk when his nose gets assaulted by the sweetest smell he has ever had the grace of smelling. It takes him less than 5 seconds to know that that smell is the wonderful scent of a newly presenting omega. He has no idea why a newly presenting omega would be outside. There are so many signs before an omega presents, so many things that clearly warn them that their first-ever heat is coming. Did this omega choose to ignore all of the signs?
Kiyoomi’s brain is foggy. He can hear his muddled thoughts getting less and less comprehensive by the second. With as much brain power as Kiyoomi can muster, he is able to adjust his mask and hold his nose as he speeds up his steps.
I’ve got to get away from here. I’ve got to get away from here. I’ve got to-
Something that came from out of nowhere crashes into Kiyoomi. It’s not enough to topple him over, but it is enough to cause a sharp pain near his ribs. He looks down, fully prepared to yell at whoever just ran straight into him, but comes short at the sight next to him.
A little boy, sticky with sweat, covered in tears, and dripping slick through his pants.
Kiyoomi sees red as the sweet smell from before hits him like a brick. His fangs are bared, a low growl coming from his chest as he fights with his inner alpha inside his head.
His alpha was telling him to fuck the little omega right here in the street while the normal side of his conscience tells him to grab the boy and head home. There was nothing inside of him that was telling him to just walk away. No voices in his head telling him to back off, and no angel on his shoulder convincing him to resist his urges. Kiyoomi takes one moment to try and search for that voice of reason until he looks down and completely loses hope. The little omega was whining, writhing, mewling, on the ground. Kiyoomi’s mouth runs dry when he notices that the boy is grinding on his shoe. He can guarantee that the omega has no idea that he’s even doing this, but Kiyoomi decides it’s as much consent as he needs.
He reaches down and hauls the boy up by the scruff of his neck. With the hand that’s not holding the child (who was pretty tall and significantly difficult to hold on to), he unzips his hoodie. Using quick and careful movements, Kiyoomi maneuvers the omega so that he’s straddling his waist, then zips the hoodie back up, over the child.
Thank God for laundry day forcing me to wear this awful oversized rag of a hoodie. Kiyoomi thinks to himself as he speedwalks back toward his apartment.
The little omega is hot and he clearly doesn't enjoy being wrapped up in another layer of heat. That is until he takes a deep breath in and inhales Kiyoomi’s pheromones. Instantly the omega's eyes grow wide and he looks up to Kiyoomi with a mix of fear and curiosity.
Kiyoomi tries to ignore him, but the omega's curiosity must have gotten the better of him because suddenly Kiyoomi feels the omega grind against his dick. With a growl, he wraps his hands around the omega’s waist, keeping him still.
“Alpha,” The little boy whispers. Kiyoomi’s blood runs cold. “Alpha, alpha, apha,” He whines. “Help me. Please alpha.”
Kiyoomi growls a vicious growl from deep in his chest but just continues his trek down the street. He’s almost home, he just has to make it past one more corner then he will reach his apartment building, he can do this.
The little omega is freaking out. One moment he is mewling and writhing, and the next he is purring, releasing out his sickly sweet peaches and cream scent that has Kiyoomi throbbing in his pants. This omega is as fresh as fresh gets and he has wandered straight into Kiyoomi’s arms.
Finally, Kiyoomi reaches the front door of his apartment building and he punches in the code as fast as he possibly can. He sees two other people waiting for the elevator and groans, deciding to just skip it and go straight for the stairs.
The stairs were a mistake. Every single step Kiyoomi bounds over has the little omega jostling around, dripping crotch spreading even more slick over Kiyoomi’s clothed dick. When the omega moaned, it echoed through the entire stairwell.
“It hurts, it hurts. Please alpha.”
Kiyoomi had to tighten his grip as the omega was now thrashing around, back arched away from Kiyoomi, head flinging around. His eyes were shut and there was drool dangling from his mouth, and Kiyoomi would be disgusted if this little pup wasn’t the cutest, sexiest, most fuckable omega to ever cross his path.
Reaching into his back pocket, Kiyoomi pulled out his apartment key, shoving it into the lock and turning it with more force than necessary. He carried his new treasure into his home. Kiyoomi barely wastes enough time to close and lock the door before he heads to his room. He unzips his hoodie with haste and drops the squirming omega on the bed.
“Do you want me to help you?” Kiyoomi asks, walking around his room and picking up anything that might be covered in his scent. “I need you to say it, Omega. I can’t help you unless you say I can.”
“Alpha,” The omega keens, rubbing his nose into the bedding as if he’s already addicted to the alpha's scent. “Help me Alpha. Please.”
Kiyoomi places a heap of dirty laundry onto the bed, spreading it around and creating his own version of a nest. He wants this omega to be ruined for anyone else, needs him to be thoroughly addicted to his alpha scent.
“Alright baby, I can help you.” He climbs into the bed. “Since you’re asking so nicely.”
Without any more thinking, Kiyoomi grabs the little omega’s pants and pulls them off, tossing them into a random corner of the room. Somehow, the scent gets stronger and Kiyoomi can feel his feral instincts kicking in like never before.
Not once has he ever wanted to ravish an omega as he does now. He wants to sink his fat cock into the little boy's juicy cunt and fill him up until he’s pregnant and full. He wants to mark the pup as his, stake claim on his baby-smooth skin, and ruin his virgin hole.
“Hurry, Alpha.” The omega whines.
“Kiyoomi. My name is Kiyoomi sweetheart.”
“Kiyoom– Kiy– Omi. Omi please.” Kiyoomi watches in fascination as furious tremors take over the omega causing him to thrash and thrust his hips in the air.
Kiyoomi almost reaches out to push him back down, but then the omega is turning onto his stomach and presenting. Actually presenting himself to Kiyoomi. This sends Kiyoomi’s alpha into an absolute frenzy.
As if being controlled by an unidentifiable force, Kiyoomi finds himself draped over the little boy, one hand reaching for his hair so Kiyoomi can push the omega’s head further into the sheets.
“Good omega.” He growls.
The omega manages to turn his gaze to Kiyoomi, and in a moment of clarity, he whimpers. “Atsumu. My name is Atsumu.”
Kiyoomi bends down until his nose is brushing against Atsumu’s hair. He inhales deeply, dizzying at the scent. “Atsumu. I’m going to help you feel better, okay? Just be a good boy and let me take control. He leaves Atsumu on the bed and it takes more willpower than anything he has ever had to do.
As fast as Kiyoomi can, he strips off all of his clothes. He paces to the other side of the bed and reaches into the nightstand drawer, digging around for a bottle of lube. The alpha's hands are shaking so much that when he finally pulls out the bottle, he fumbles and watches it fall to the floor. He bends down to pick it up, and when he turns around to once again admire his prey, his mouth runs dry.
Atsumu, his sweet, darling, newly-presented omega, is three fingers deep into his cunt. His hips are rocking back with every thrust, desperately trying to make the pain of his heat go away. The boy's eyes are barely open and all Kiyoomi can see are the whites because of how far back they rolled. There is drool dribbling into Kiyoomi’s sheets as the omega seems incapable of keeping his mouth closed.
All of this is driving Kiyoomi mad, but the cherry on top of the cake would be the lewd noises Atsumu was making. It wasn’t quite a moan, more like high-pitched keening. One of the thrusts must hit Atsumu’s prostate because he squeals. In between those little noises, Kiyoomi can make out quiet “omi, omi, omi’s”
Any resolve that may have possibly been left inside of Kiyoomi snaps. He takes one look at the amount of slick pouring out of Atsumu and throws the lube back onto the ground. It wouldn’t even be necessary.
Kiyoomi reaches over and grabs Atsumu’s wrist, pulling until the omega is no longer able to finger his pussy. “If I see you try and satisfy yourself again without my permission, I will tie you up and let you suffer without anything to fill up your greedy cunt.” He punctuates his sentence with a light slap to Atsumu’s hole. “All you need, and all you will ever need, is my cock, and my knot.”
Atsumu pulls against Kiyoomi, but he barely even moves an inch. “I need–” another tremor wracks through his body. “I need Samu.”
Kiyoomi has no idea what Atsumu is talking about, nor does he care. What he does care about, is his dick that is now resting right in between Atsumu’s plump, smooth, ass cheeks. It’s already getting covered in slick and he hasn’t even gone inside yet. That would have to change.
Slowly, or about as slow as he can manage, Kiyoomi finally pushes into Atsumu’s wet heat. He makes it in about three inches before he has to stop and hold himself back.
Kiyoomi wraps a fist around the base of his cock, his knot already forming. If he doesn’t get all the way into this little omega’s cunt so he can knot him and pump him full of cum because of his own damn horniness, he will never forgive himself.
Atsumu is panting, eyes blinking rapidly while tears stream down his face and into Kiyoomi’s sheets.
“You look like you’re already feeling full,” Kiyoomi coos. “I’m barely even halfway in, darling. And that doesn’t include my knot.”
Atsumu moans, deeper and louder than the tiny squeaks from before. “Give it to me,” He pants. “All of it.”
Kiyoomi scoffs. “Like you get a choice. You’re my little omega bitch now.” Then he pushed even further in. The sound Atsumu makes almost makes Kiyoomi have to pause again, but he finds it in himself to keep going.
Once he is fully seated in Atsumu’s pretty, pink cunt, Kiyoomi pulls out slowly. Atsumu tries to chase it but doesn’t need to wait long before Kiyoomi is thrusting back in, apparently hitting Atsumu’s prostate dead on.
The little omega screams, clawing at the bed before suddenly going completely limp besides occasional jolting as his orgasm takes over his body. Kiyoomi fucks him through it, hitting deep and hard a few times before his knot pops into Atsumu’s pussy and he can feel his cum spilling out in waves.
Kiyoomi isn’t sure, but he thinks this is the most cum an omega has ever been able to milk out of him. He just knows Atsumu would probably feel it sloshing around in his little tummy if he wasn’t so full of alpha dick right now.
As soon as he’s done catching his breath, Kiyoomi wraps his arm around his omega and flips them over. With very careful movements, he manages to situate himself against the headboard, with Atsumu sitting on his lap, stuffed full of his knot.
Atsumu’s head lolls forward before tilting back and resting on Kiyoomi’s shoulder. “Alpha,” He purrs as he sticks his nose into Kiyoomi’s scent glands. Kiyoomi moves his head so that it would be easier for Atsumu to relish in his scent. When the omega finishes, he relaxes completely into Kiyoomi’s chest and purrs in a constant, steadying rhythm.
If he was being honest, Kiyoomi thought that getting this omega attached to him would be harder than this. From the looks of things, he’s already at least halfway to having Atsumu completely brainwashed into being his little omegan toy.
Kiyoomi reaches around and gently runs his thumb over the nub that is Atsumu’s nipple. The omega jolts awake immediately, but the purring doesn’t stop and after a few moments he relaxes back into Kiyoomi.
“One day, when I have successfully bred you full of my pups and you’re all fat and pregnant, these slutty tits of yours are going to be nice and fat,” Kiyoomi muses. He can feel the omega’s cunt start to produce more slick. “And when they are at their biggest, I am going to fuck your tits and make you drink up all of my cum after I finish on your pretty face.”
Kiyoomi’s knot seems to be almost done deflating, and just in time too because Atsumu seems like he’s ready to go again already.
“Look at you. Just a cock-dumb, knot-obsessed, omega. Perfect for me to breed. Just like you were born to be.”
Atsumu moves his hips experimentally, gasping at the feeling of Kiyoomi’s huge dick moving around inside of him.
Kiyoomi wraps his hands around Atsumu’s waist, growling in pleasure when he realizes they wrap all the way around. He squeezes lightly and that’s when he realizes it. One more small push to Atsumu’s tummy confirms it. Kiyoomi’s dick is causing Atsumu’s stomach to bulge.
Never in his life has Kiyoomi felt as turned on as he does right now. Without warning, he grips the omega’s hips and pulls him up just to slam him back down, effectively impaling the little pup on his dick. He does this over and over, watching Atsumu flop around as he is manhandled to bounce up and down on the alpha’s cock.
“You’re like having a cute little human fleshlight, baby. All for me to use.”
Kiyoomi pinches both of the omega’s nipples and watches in awe as Atsumu arches his back like he was born to do it. When Atsumu’s second orgasm takes over, he’s unsurprised to see him pass out, going limp and falling back into Kiyoomi’s chest.
As carefully as he can, Kiyoomi pulls out of Atsumu and lays him down on the bed. He grips himself and begins to stroke his hard cock over the omega's peaceful body. He bites his lip and cums with a groan, spilling his white load onto the pup's torso.
Now he needs to take a shower.
_____
Kiyoomi wakes up to probably the best sight any alpha could ask for. Atsumu is desperately grinding on Kiyoomi’s thigh, facing away so that Kiyoomi gets a perfect view of the omega’s leaking cunt.
“Well good morning to you too,” Kiyoomi grumbles, morning voice sending visible goosebumps down Atsumu’s spine.
“G’mornin Omi,” Atsumu says, still grinding down furiously. It’s only a few more seconds before Atsumu is cumming, gasping, and panting as he chases his orgasm.
“What a good omega, getting off on riding my leg like a bitch in… heat.” Kiyoomi just now notices something. Atsumu’s smell is no longer strong like the scent of an omega in heat, it’s just a normal peachy scent, maybe a tiny bit heightened from arousal. “Is your heat already over?”
“Already?” Atsumu laughed. “It’s been five days. Ya saved me alpha, I couldn’t make the pain go away.”
So if Atsumu was no longer in heat, and yet he was still here in Kiyoomi’s bed despite having nothing stopping him from leaving, does that mean…
“Are ya gonna mate me now?”
Kiyoomi’s inner alpha soars. It was that easy.
“Soon, my love.”
“Then…” Atsumu quirks his head to the side and shoots Kiyoomi a hopeful look. “Can we go find Samu now?”
“Who?” Kiyoomi stands up and stretches before heading to his wardrobe. In the bottom drawer, there are clothes saved from when Kiyoomi was in high school. It will still be a little too big for the omega, but it will have to do. He throws an outfit over to Atsumu.
Atsumu catches the pile and begins to pull the shirt over his head. “My twin.”
Kiyoomi freezes. Atsumu has a twin? This is good– no, this is great news. Kiyoomi can already picture it now, two little twin omegas tied up, swapping spit while Kiyoomi takes turns fucking them into oblivion.
“I’m a lil worried ‘bout ‘im.”
“How come?”
Atsumu finishes getting dressed. “Well, we both presented last week. The thing is, he presented as an alpha. That’s not normal for twins.”
Kiyoomi’s brain runs short. His twin is an alpha? That’s odd, and it sure does change things, but Kiyoomi doesn’t see why he can’t still go through with his original thoughts.
He has always been interested in the art of bitching after all.