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It wasn't Katsuki's fault that his daddy was so attractive. The Alpha was all soft smiles and warm hugs, goofy jokes and handsome muscles. Katsuki's dad was ripped, and so, so pretty with his red hair and doe eyes. Katsuki might've been young, but he was an omega with needs and he craved his daddy's knot.
Katsuki had always loved his daddy. His daddy knew what was best for him and he knew that one day Katsuki would become an amazing omega mate for a lucky someone, but what he didn't know was that Katsuki only had eyes for him.
When Katsuki got home from school, he ran into his arms. "Daddy! Daddy! I made this for you!" Katsuki wasn't normally sweet to people, his default emotion being anger, but his dad was different from other people. Eijirou shot his son a sharky grin. "Yeah, baby? Show me!" Katsuki thrusted the gift into his daddy's big hand. It was a bracelet, red and orange with a little gear charm on it, the gear was crimson with an orange x through the middle. Eijirou gasped dramatically and held it close to his chest as a small tear formed in his eye. "This is the best gift I've ever gotten." He dipped Katsuki and planted kisses all over his face. "Thank you, baby!" He slid it on. Katsuki giggled. His daddy was so silly.
Katsuki was in heat and his omega was screaming at him. His daddy was such a strong, handsome mate. He took such good care of Katsuki, calling him his pretty baby while stroking his hair. He knew what he was doing, he had to. Katsuki purred and moaned so prettily as he worked his fingers in and out of himself, imagining his own father taking advantage of him. "Shhh~ it's okay, katsu... we're gonna do something together that mommies and daddies do... it'll help with your heat..." he imagined his daddy sliding a huge warm hand down his shorts, stroking his tiny pussy lips.
"...You wanna be a mommy, katsu? My pretty little baby mommy..."
"Yes! I want to be a mommy! I'll be the best for you, daddy!" Katsuki cried out.
"I know you will, my beautiful baby boy." The Alpha in his imagination said with a smile.
His daddy had such a pretty smile, his teeth were all sharp and screamed 'Alpha'. They would leave a perfect claming bite.
Eijirou kicked off his shoes, back home from work. His pretty baby was due for a heat soon, and he had to stop by the store to buy his poor kat a knot toy. Eijirou tried his hardest to be a good dad to Katsuki. He loved his son so much, more than he would ever love anyone. Eijirou was filled with pride when his sweet little boy only allowed his daddy to touch him, to take care of him. It was slightly concerning, however, when Katsuki's teacher called Eijirou to tell him that they did a project where they had to draw themselves in the future and Katsuki drew them married. Eijirou didn't think too hard about it, laughing it off as kids being innocent and Katsuki being confused.
Katsuki could smell his daddy, back home from work. He ran out of his room and into Eijirou's arms. "Please... help me, daddy..." Katsuki whined pathetically.
Eijirou was suffocated by the smell of sweet omega heat and the undertone of slick. His instincts told him things that made him feel guilty and disgusted in himself. He suppressed a growl as he bit his lip. "I... I know it's tough baby... I'll get you some food and a knot toy, sweetie..." as much as he wanted to help Katsuki in other, better ways, he couldn't. Katsuki was his SON, his baby. He wasn't supposed to be turned on by him like some... sick pervert. He hated himself. He was supposed to be a father, not some gross knothead that attacked poor little babies at the first whiff of arousal.
Katsuki released a deep whine interrupting Eijirou's thoughts. "Noooo... daddy, please... I don't want the fake knot! I want you..." Eijirou gulped. "K-kat, baby... you don't want me. I'm your daddy! I know it's tough. You're in heat and there's a strong alpha right in front of you, but we can't.... do that." Katsuki looked like Eijirou had just punched him. His little eyes welled up with tears and his eyebrows furrowed, lip jutting out in an angry, wobbly pout. "Why not!?" He cried. Eijirou stuttered, he didn't really know how to explain the concept of incest to his innocent baby. "B-because baby, I... you're my son, and parents shouldn't... be with their kids like they are with each other. A-also you're my baby! You.... are way to young to be taking knots from anyone!" Katsuki just pouted even harder. "That's stupid! I love you more than any stupid alpha! I know you'd take care of me!" Eijirou just ruffled his hair. "You'll change your mind when you're older..." he smiled warmly. "You'll be so embarrassed about thinking you had a crush on me." Katsuki scowled at him. He would never change his mind! His daddy was the best mate ever!
Later that night when Eijirou finally fell asleep, Katsuki quietly pushed his door open and toed inside. He loved his daddy, but that didn't mean he thought he was smart. His daddy was kinda dumb. He needed Katsuki's help to realize they belonged together. He crawled into bed beside him, slithering under his arm, becoming the little spoon. Their bodies were pressed closely together, and Katsuki took a second to just appreciate the warmth.
Eijirou woke up to a tiny soft butt rutting against his raging hard on. He sleepily wrapped his hands around the tiny, tiny waist, and shoved his hips forward, grinding against the body. "A-ah! D-daddy!" Eijirou's eyes snapped open to the horrifically beautiful sight of a naked Katsuki fingering his little pussy with Eijirou wrapped completely around him. Eijirou quickly scrambled away, falling off the bed. "Baby! Oh my god I'm so sorry! I... I'll leave you to it!" He made a beeline for the door before a little pathetic sob rang out. Eijirou turned to see Katsuki looking at him so heartbroken. "Daddy... please..." he whimpered.
This was one of the hardest things he ever had to do, but he ripped himself from the door and walked away from his baby to get the fake knot. "Noo! Daddy! Please, I'll be a good boy for you!" Katsu was crying, crying because Eijirou was being so cruel to him, denying him what he wanted, but it was for the better that Eijirou didn't take advantage of him. Because Eijirou had to remind himself that's what this was, him taking advantage of his sweet and trusting boy.
Katsuki's sobs wracked his body, little whines and hiccups breaking his daddy's heart. His omega wailed with the rejection. Katsuki tearfully begged for Ei again. "P-please?... please daddy, it hurts... please make me a mommy... a mommy for you... please daddy?" His sweet baby didn't know what he was asking for. "Katsuki, baby..."
"Please, daddy... please..." Katsuki begged. His little pussy was flushed pink and so wet, his chest was heaving and his eyes were so teary and helpless. Eijirou's claws dug into the wall with the strain of holding himself back. But Katsuki's legs spread open and his little hand came down to open his puffed lips, showing off the deepest pink parts. "Daddy... help me... it hurts~!"
Eijirou couldn't take it anymore. He growled and pinned his sweet boy down, ripping his hand away from his little cunt before he kissed all over it, licking and sucking on the sensitive lips. Katsuki squealed in delight as his daddy devoured his pussy.
"Daddy~" Katsuki whined as his slick coated Eijirou's face. Eijirou lapped deeply into his poor baby, trying to soothe the ache away. Katsuki's little fingers tangled in Eijirou's hair as he pulled him closer.
"A-Ah! Daddy! Please... faster!" Eijirou purred. His baby's cunt was so good. It was so sweet and juicy.... he did as Katsuki demanded. His tounge moved faster as all his thoughts melted. Why did he ever resist this? His baby deserved everything he wanted, he was a brat, and Eijirou... Eijirou LOVED it. He loved it when Katsuki was just so angry and unhinged, throwing a tantrum and effectively scaring every adult in a hundred mile radius just to calm down immediately upon seeing Eijirou and turn into a sweet little pliant angel for his daddy. It made him feel.... good, special... possessive. His baby was basically telling everyone that he only listened to his daddy. His alpha. Eijirou worked in a finger and Katsuki quivered in his hold. "Mmhh! Ohh my god, daddy!" He squealed as slick gushed out of him, his walls spasming and his eyes rolling back. Eijirou licked all of it up, his baby whimpering from the sensitivity.
Eijirou flipped him over and hiked his hips up, putting him in the perfect mounting position. Katsuki looked back at him with a cute little pout. "I wanna face you, daddy!" Eijirou growled hungrily as he flipped him back over, pinning his knees to his shoulders and straddling him in a mating press, lining his angrily throbbing cock up to Katsuki's little twitching hole and slamming down into him. Katsuki squealed as his daddy drilled in and out of him, his small pussy trying it's hardest to accommodate such a huge intrusion. Only half of Eijirou could fit inside his baby, but he didn't care. It felt so, so good to finally be inside his son's sinful cunt. He kept going, faster and faster and-
"OHHH DADDY!"
Suddenly Katsuki's cervix gave way and Eijirou's cock shoved in and out of his womb. He could fit about two thirds inside before he was pressing against Katsuki's diaphragm. He resumed his harsh pace as Katsuki wailed in pleasure. Katsuki gushed and squirted and shook around him, but he just kept going, faster and harder, ruining his baby.
When Eijirou finally felt his knot start to form, he rustled Katsuki's hair gently. "B-baby... let... let me knot you..." Katsuki whined and nodded as he squirted again. His daddy was brutal. Eijirou kissed him so tenderly as he slowly inched in. It wouldn't fit. Eijirou's dick was too big, Katsuki's pussy too shallow. "Fuck!" Eijirou growled in frustration. Katsuki snuck his little hand down and wrapped it around his daddy's knot, squeezing lightly. Eijirou kissed his baby again as he released his cum, filling Katsuki so much, his tummy was a little distended. He pet his hair as his hand went down to tease Katsuki's clit. "You're so sweet and good, baby... I love you so much..." Eijirou purred. " I... I love you too, Daddy..." Katsuki whimpered, cumming again.