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Katsuki's new stepson was a bitch.
Katsuki was almost certain that he was his real son. He had already fucked Inko, the woman he married, a few times when they were in school, and when he needed a quick, political marriage, she showed up with a teenage omega in tow, Izuku.
It was a good arrangement: Katsuki gave her a small company to play at running and she fulfilled her duties as a wife while staying out of his way. During the negotiations, Katsuki truly believed it would work, that his future stepson would be nothing more than a ghost in the house and he would barely have to interact with him.
But then, on the day the two omegas moved into the mansion, Katsuki came home from work during his lunch break while the mother and son carried boxes in and out under the scorching summer sun. Izuku was wearing tight little shorts that were stuck in his ass and a crop top that rode up dangerously every time he moved too much, threatening to reveal the firm, bulky tits of a male omega. The boy’s green curls were all matted with sweat, and the freckles on his face were darker from the sun. His scent spread through the house and around it like a drug.
Izuku was at the perfect age to be bred, actually, he should already have a litter. He was the perfect kind of omega for that: young, with omega fats in all the right places and wide hips ideal for giving birth. Katsuki had no idea how he hadn’t gotten pregnant yet, he was already 16, there should have been lines of alphas waiting for a chance to knot him.
He understood the difficulties these alphas must be facing once he started spending time with the brat. He was skittish, provocative, mockingly called him daddy and loved stirring up trouble with Katsuki and his mother. The alpha was reaching the limit of his patience with him, on edge and ready to beat Izuku at the slightest sign of insolence. The only thing missing to keep that omega in line was to plant a litter of chubby pups inside him, just as an omega his age should be.
That week was especially tough. Izuku had already fought with his mom over school, had argued with one of the housekeepers about doing laundry and Katsuki became the target when he got home in the middle of the day after spending more than twenty-four hours resolving an international issue at the company and the teenager stormed over to him, still wearing his school uniform and with his face red with anger.
Katsuki took off his suit and threw it on the floor, stressed out, sleep-deprived and too angry to care. He had already made it crystal clear that if Izuku tried any of his usual antics on him, he would step up as the alpha of the house and teach the brat his place.
“What did you do with my iPad?”
It had to be a joke. Katsuki spent an entire day trying to juggle a million-dollar problem while dealing with foreign old alphas who thought they knew better than everyone else, only to come home and be accused of stealing a damn iPad. He felt a growl rise in his throat and was about to grab Izuku by the scruff of his neck and make him submit when Inko came down the stairs.
“I took your iPad, Izuku. Now apologize to your father like a good omega and never raise your voice at him again.”
The younger one looked outraged, and Katsuki himself was confused. Inko was in it for the money and the comforts, she would never bother to defend him from anything, especially not from her own son. Izuku must really be a pain in the neck if even she decided to get involved.
“Mommy!”
With an annoyed look on her face, the older omega motioned for Izuku to be quiet and walked past the two of them, her heels clicking as she descended the steps in front of the mansion toward the car.
Katsuki closed the door behind her and walked to his office, flopping into his chair as he loosened his tie. All he wanted to do was take a shower and sleep for 12 straight hours, but he still had a few messages to send before he could finally put work aside for a moment, and if he went to his room, he’d fall asleep right away.
The alpha watched the laptop turn on without really focusing on anything when the door opened and Izuku’s scent wafted in before he did. The omega had a pout on his lips and looked extremely upset. He let out a little squeal and jumped when the alpha growled at his presence.
“What the fuck do you want?”
“Mom said I have to apologize.”
“So do that and get out of here quickly. Go make some babies like the rest of the omegas in your class and stop bugging me.”
Izuku let out a small, angry omega growl, but didn’t respond as he approached his stepfather (or father, who knows?) and knelt down beside him on the chair. Katsuki suddenly became much more alert, swiveling in his chair to face him and trapping the younger boy between his knees.
The alpha couldn't figure out what kind of apologies he usually asked for that involved getting down on the knees, but if the sassy teenager wanted to bow to him then Katsuki would gladly accept it, ready to commit the image to memory and enjoy it the next time he was fucking someone and needed some extra stimulation.
Glaring up at him with angry eyes, the omega reached for his pants and tried to unzip them. Katsuki knew he should be alarmed, or shocked, or something like that, but he was too tired and had always wanted to fuck that attitude right out of this omega, so if the boy himself was trying to shove his dick in his mouth, so be it.
Katsuki let him pull his pants and underwear down, helping by pushing them down to his ankles. Izuku crawled closer, his gaze now far from the alpha’s face, focused on his soft dick, which was beginning to twitch slightly with life. His green eyes sparkled with wonder, perhaps a little in shock.
“Wha-”
Katsuki grabbed a strand of the boy’s green curls between his fingers and pulled it, forcing the younger boy to look him in the eye so he could make himself perfectly clear.
“Is that how you apologize, omega? Just staring at my dick isn’t going to do anything for me, start moving and get me going with your throat.”
Izuku squirmed in his grip, grumbling, but when Katsuki tightened his hold even more he gave in and relaxed, his soft hands gripping his cock with a slight tremor.
“That’s not going to fit in my mouth.” And then, in an even quieter awe whisper, “It’s not even hard yet.”
The alpha chuckled, licking his lips as Izuku began to dry-jerk him, moving his hands up and down in an exploratory manner, looking enchanted as his cock grew harder and harder.
“You’ve never given a blowjob, omega? For God’s sake, you’re already 16, you should already be taking fat dicks even up your ass by now.”
“I’ve given a blowjob before!” As if to prove his point, Izuku spat on the head of the alpha’s cock and began to jerk him off more vigorously now that it was better lubricated. “Mom said I had to apologize to the principal, so I took his knot in my mouth and he didn’t suspend me.”
Katsuki could imagine that only something like that would be able to keep Izuku in school. Over the past few weeks, he’d been picking fights with the alpha teachers who tried to punish him, picking on his pregnant omega classmates and talking back to the staff. Katsuki told Inko he was sure it was jealousy, frustration that he was the only omega in his class who didn’t have a litter yet or wasn’t expecting one. Inko replied that Izuku wasn’t that kind of omega, but there was proof that Katsuki was right. Of course.
Omegas existed to be knotted up and to carry litters of chubby pups. That was what all omegas wanted, what they needed, and sometimes they were too clueless to go after it on their own and needed an alpha to pick them up so they could finally be happy.
That was why Izuku had been acting so annoying, Katsuki was sure of it. Seeing all his friends reach their peak as omegas at the ideal age while he was left out must have been frustrating, and since there was nothing more certain than receiving support and encouragement at home, Katsuki would step into his role as the alpha of that little pack and give the youngest omega what he didn’t even know he needed.
“Spit on it again.” Izuku obeyed the order immediately, watching the spit slide down his now fully hard cock, then looking up at the alpha, waiting for further instructions. “You took your principal’s pathetic little knot in your mouth because it was tiny.” Katsuki guided the omega’s head toward his cock, watching with satisfaction as he opened his mouth to take it without any prompting. “It’ll take some practice to take mine, but I think your pussy can handle it.”
Izuku looked up, alarmed by his statement. He was about to say something about how it was just a apologize blowjob and had nothing to do with his pussy, but his lips were stretched tight around the alpha’s cock and his tongue was pressed against the weight of the rock-hard dick, so all he could manage was a whimper.
The alpha pushed the younger boy’s head until it reached the entrance of his throat, halfway down his cock, and clicked his tongue in disappointment at having hit the back of his throat so soon. Izuku’s teary eyes seemed to take this as a challenge, and the omega began to choke, trying to take his stepfather’s cock deeper and deeper.
Katsuki had to give him credit, the boy had determination and zero gag reflex working in his favor. The alpha knew he was made for this, he was too much of an omega for not to be a perfect cooksleeve. The alpha lifted his hips, thrusting with a certain brutality.
The thrust made Izuku whine around the cock, the sound mingling with wet gagging noises, tears streaming down his face and his eyes wide with choking as he gazed up at the alpha from beneath long, wet lashes. Katsuki couldn’t resist and thrust once more before pulling Izuku away by the grip on his hair.
The omega fell backward onto his knees, coughing violently and glaring at his stepfather with his usual anger. He was a mess, his face all red and streaked with tears and drool, his curls all tousled from Katsuki’s grip.
“You can’t just shove that energy drink can down my throat like that, you crazy.”
Curious, Katsuki looked down at his own cock, wet and dripping pre-cum from the tip, and came to the conclusion that maybe it really was the size of an energy drink can. Now he understood why so few omegas were able to take his knot.
Leaning forward and cupping Izuku’s face, the alpha growled into his ear, exhaustion and the urge to come mingling in the depths of his eyes. He had no patience for a rebellious omega trying to take control of the situation. Katsuki was the alpha here, and alphas took what they wanted.
“If you get down on your knees for me, you have to be ready to take whatever I want to give you.”
“You’re not my—”
“Legally, I’m your guardian. I’m your daddy, Izuku, your alpha and your owner.” The omega whimpered, and Katsuki caught the scent, mingled with the omega’s defiant aroma, slick. Fresh and abundant, dripping from Izuku’s pussy as his daddy claimed him as his own. The alpha smiled. “Deep down you know your place, and you know that at this point you should already be heavy with your second litter. You were saving yourself for me, weren’t you? That’s why you never let any of your teachers get you pregnant like they did with the other omegas at your school.”
With a pout on his lips and a softer look in his eyes, Izuku nodded, his scent filling the office with a sweet fragrance.
“Yes, daddy.”
It wasn't meant to be provocative this time, just the submissive acceptance of an omega finally being placed where he'd always wanted to be.
Katsuki grunted with satisfaction, running his hand through Izuku’s hair again, this time stroking it proudly because Izuku had admitted it, before tightening his grip once more and pulling that pretty little mouth back down to swallow his cock.
Holding his cock in his other hand, the alpha ran the red mushroom-shaped head along Izuku’s cheeks, smearing even more pre-cum across his face, before rubbing his lips until they parted, thrusting all the way in at once and going a little deeper this time.
Crawling forward, the omega got as close as he could while swallowing, his nails digging into his stepfather’s thighs. Katsuki let him get used to it, steadying his breath through his nose, and when the omega looked up again with that cock-hungry gaze, the alpha grunted with satisfaction at finally being able to relieve himself.
Katsuki settled into a rhythm of hard but lazy thrusts, using Izuku’s mouth as a fleshlight while sprawled out in the chair, feeling like he could fall asleep just like that, with his stepson’s small, warm mouth warming his cock.
Izuku was choking and crying, but he held his ground without trying to pull away, like a good omega trying to make his alpha happy, and the scent of his slick just kept getting stronger and stronger. Katsuki knew he’d need some practice before he could get his stepson to take him all the way down, but it was fine for now because the alpha’s plans didn’t involve letting the omega swallow his cum today.
The most fertile period in an omega’s life was during adolescence. At Izuku’s age, an omega should be pregnant as much as possible. Young, healthy wombs needed to be constantly full to fulfill their role, and Izuku had already wasted a lot of time, so Katsuki was going to make up for that lost time for him.
When he stopped thrusting, the omega tried to push himself down, desperate to continue and whimpering as his stepfather pulled him away again. Katsuki helped him up, guiding Izuku as the omega coughed and wiped his face with the backs of his hands
The alpha folded him over an empty space on his large, tidy desk, lifting the skirt of his uniform and pushing the white lace thong, soaked in slick, to the side.
“And what about those slutty panties, huh? Are you really going to school in those even though you know I’m your alpha? I thought you were saving yourself for me, you slut.”
The sharp slap the alpha delivered to his stepson’s freckled ass echoed through the office, and Izuku whimpered and moaned, squirming under his hand as his pussy clenched against the cold air and grew wetter and wetter with every passing second the alpha’s scent lingered nearby.
“No, daddy, I only u-use it at home for you, I swear.”
“Liar.”
As punishment (or reward), Katsuki gripped his cock at the base — which was already starting to swell with his knot — and tried to shove it into the omega’s pussy all at once. He had to thrust hard two or three times before the head slipped in and he could ram his cock all the way in, the force of the thrust pushing Izuku forward onto the table.
“Daddy!”
With a scream, Izuku rolled his eyes and kicked the floor beneath him, instinctively trying to crawl away from the thick, massive cock that was cruelly tearing open his poor little pussy. His stepfather grabbed his waist tightly, holding him in place and forcing him to take the monster that was tearing through his pussy without even being able to squirm.
Katsuki’s cock was so thick that Izuku’s pussy would surely be left with a gaping hole for a while, sore every time it contracted and reminding Izuku of the emptiness his stepfather’s cock had left inside him. What’s more, the alpha was so deep inside him that the omega could feel the head of his cock brushing against his cervix.
With a satisfied groan as Izuku seemed to relax ever so slightly beneath him, the alpha withdrew all the way out and thrust back in hard, beginning to pound relentlessly against the omega’s cervix and drawing desperate cries from him, his pussy squirting slick fluid around the oversized shaft.
As the knot began to swell gradually while Katsuki pounded his stepson’s pussy with his fat cock, his thrusts began to slow down due to the difficulty the knot was having getting inside. Katsuki grunted, reaching out to grab the omega’s neck for better leverage to force his knot deeper into his pussy.
Shaking violently beneath the alpha’s large, heavy body, Izuku came, crying and squealing, squirting all over the monstrous cock. His pussy tightened as it contracted during the orgasm, and the delicious pain of squeezing something so big inside him while he squirted prolonged his orgasm even further.
“That’s fucking right, squirt all over my cock like that.”
The amount of fluid soaking his balls and Izuku’s inhumanly tight grip around his cock were enough to make Katsuki pop his knot, which he had to force quickly into Izuku’s cunt before it burst completely because he knew it wouldn’t fit inside anymore after that. The head of Katsuki’s cock was pressed hard against the omega’s cervix, pushing against it as it made room to accommodate the fat knot.
Most of the omegas Katsuki fucked couldn't take his knot, they were unable to fit his fat knot into their holes. And even if they managed to, they'd break the moment he thrust, passing out because they couldn't handle it.
When he felt the knot lock in place, at that moment when the omega’s cunt tightened around the knot to keep it inside as long as possible, Katsuki tapped Izuku on the back of the neck to see if he had passed out, but the omega was wide awake.
His mouth was open and drooling, his wet eyes were unfocused and had shades of lilac mingling with green, and his scent seemed even sweeter and more seductive than ever. He had experienced an omega fall, his brain completely overtaken by his second gender after being forced to take a nice big cock and a fat knot.
Katsuki laughed at his stepson’s predicament, giving his cheek, which was turned toward him, two light pats with the backs of his hands, then pausing to groan as the first rich wave of thick, hot cum spilled out.
The alpha closed his eyes as he came in powerful waves inside Izuku, right into his womb, flooding his ovaries with a deluge of top-quality cum. His troublesome stepson was undoubtedly getting pregnant at that very moment and finally taking on the role he was long overdue to assume.
With one last satisfied groan, the alpha held Izuku close and sat back down in the chair, amused by the omega’s surprised gasp as the pressure from the knot inside him increased even more now that he was sitting on it, the weight of his entire body keeping him firmly in place.
The omega whimpered as he spread his legs as wide as he could and writhed, trying to relieve the intense pressure on his pussy and, as Katsuki later noticed, on his stomach.
When he pulled the omega’s torso against his chest to keep him still, the alpha noticed the flat stomach now slightly rounded with the weight and volume of semen trapped inside his womb with nowhere to go. It grew a little every time Katsuki released another stream of fresh cum. It almost looked as if Izuku already had a chubby little baby growing inside him.
With one hand on his neck, pulling the omega’s head to rest against his shoulder, Katsuki purred in his ear.
“Keep it up, omega. The more you milk me while writhing like that the more cum I’ll shoot inside you and the bigger your litter will be.”
“This is too much, daddy.” Izuku whined.
“Yeah, that’s right. But you can take it, omegas are made to take it. You’re going to carry three giant pups for me inside here without complaining, aren’t you?”
“As many as daddy wants.”
“That’s a good omega.”
Actually, there were four puppies, as if to make up for the fact that Izuku should have had a few babies by now. Izuku grew huge in just a few months and his little tits swelled with milk within the first few weeks.
Katsuki knotted him whenever he could, since hot cum deep inside the womb and intense contact with the alpha sire were important for keeping the pregnancy as smooth and healthy as possible. The last thing Katsuki wanted was a stressed-out wife and a pregnant teenage omega causing a scene at home.
The omega told his mother that the one who had gotten him pregnant was one of the school’s alpha teachers, specifically a blond one. It was a safe excuse; half the omegas at the school were heavily pregnant with the teachers’ puppies, so no one would suspect anything, it was normal.
Izuku became docile and then said. The alpha couldn't tell if it was the pregnancy or the daily thick fat knots he had to hug with his pussy, but the omega turned into an obedient, submissive little thing.
When he had the babies, his tits were always out with heavy pups clinging to his nipples all the time. When two finished nursing, Izuku would hand them over to the nannies and it was time to nurse the other two. Even so, he was still always leaking milk and got into the habit of milking himself to relieve the pressure every morning before going to school.
Katsuki loved the milk, he liked to put it in his coffee. And when his wife wasn’t home during this ritual, Izuku would milk himself directly into his stepfather’s cup, whimpering and moaning until he told him to stop.
When the first litter was about six months old and starting to sit up on their own, Izuku was already getting heavy with the next one. This time, he told his mother that an alpha on the street had cornered him in an alley when he caught the scent of his leaking milk.
It was a very common story, and the supposed alpha would be untraceable that way, so once again no one could question why all of Izuku’s babies were blond and had red eyes.