The morning light cut through the study curtains in sharp, dusty beams, painting stripes across their naked, tangled bodies on the floor. Izuku stirred, his cheek pressed to the firm warmth of Katsuki’s chest, the steady thump of his heart a familiar rhythm. His hand, splayed over Katsuki’s ribs, shifted. His thumb brushed a ridge of raised, pale skin.
He went still. His green eyes blinked open, focusing. It was a scar, maybe four inches long, thin and surgical-looking, riding the curve of Katsuki’s lowest rib on his left side. Izuku had never seen it before. His finger traced it, a feather-light touch.
Katsuki’s entire body tensed. His breath hitched—a tiny, sharp intake that sounded like pain. In the brutal morning light, his guard didn’t just drop; it shattered. His red eyes were wide, fixed on the ceiling, seeing something else.
“The second guy,” Katsuki said, his voice rough with a sleep he hadn’t gotten, rough with a shame he’d never shown him. It was just a statement. A confession exhaled into the dust motes. “Shinso. He fought back.”
Izuku’s finger froze on the scar. He didn’t pull away. He felt the truth of it, cold and metallic, sink into his gut. This wasn’t a childhood scrape. This was a wound from a man Katsuki had… removed. For him. His baby boy, carrying a mark from killing for him. “Kacchan…”
“Had a knife. Got lucky.” Katsuki’s jaw worked. He still wouldn’t look at Izuku. “Stupid. Should’ve been cleaner.”
“Does it hurt?” Izuku asked, his own voice soft, the question absurd. He leaned up, his curls messy, and placed his lips against the scar. He kissed the length of it, a slow, deliberate press of his mouth to the proof of Katsuki’s violence.
A shudder ripped through Katsuki. His hand came up, tangling in Izuku’s green hair, not to pull him away, but to hold him there. “No,” he grunted. “Not anymore.”
Izuku’s hand lifted from the scar and came down in a sharp, open-palmed slap against Katsuki’s bare chest. The sound cracked in the quiet room. “Don’t you ever let anyone hurt what’s mine again!” he scolded, his voice a high, maternal command that didn’t match their nakedness. He pouted, his full lower lip jutting out, freckled cheeks flushed. It was the same look he’d used when Katsuki skinned his knee at seven.
Katsuki didn’t flinch. The slap barely registered. He stared up at Izuku, his red eyes wide, then a low, disbelieving laugh rumbled in his chest. “That’s what you got from that? Not ‘oh god, you killed a man,’ but ‘don’t get cut’?”
“I know what you did.” Izuku’s pout softened into something darker. He shifted his weight on Katsuki’s hips, his own arousal a slick, undeniable heat between them. “I know why. He touched me. He thought he could have what’s yours. So you made sure he couldn’t.” His small hands framed Katsuki’s face. “My violent boy. My protector. But this,” his thumb brushed the scar again, “this is a mark on my property. I don’t like it.”
“Your property,” Katsuki repeated, the words a guttural rasp. His hands came up to grip Izuku’s thick thighs, fingers digging into the soft flesh. “Fuck, Mommy. Say it again.”
“You’re mine, Kacchan. All of you.” Izuku leaned down, his curls brushing Katsuki’s jaw. “Now tell me about the others. The ones who didn’t get a chance to fight back.”
Katsuki’s breath hitched. The vulnerability from moments ago was gone, burned away by Izuku’s possessiveness. “What do you want to know?”
“Everything.” Izuku’s mouth was at his ear. “How many? How did you do it? I want to know what my son did for me.”
“Four.” The number fell like a stone. “Not counting the old man. Four who thought they could take you to dinner, put their hands on you… dream about you.” Katsuki’s voice was clinical, detached. “The first two was easy. Brake lines on their cars. The third was a pill overdose. He was a sad drunk anyway. The fourth…” He trailed off, his hands sliding up to cup Izuku’s ass, kneading. “The fourth, I just made sure he lost everything. Job, reputation. He moved to fucking Hokkaido.”
Izuku listened, a strange, warm pride coiling in his gut. He rocked his hips slowly, grinding his wet pussy against Katsuki’s stomach, leaving a shiny smear. “And you were never scared?”
“Only of losing you.” Katsuki’s gaze was ferocious, unwavering. “They were just obstacles. Removing them was… maintenance. Keeping my world in order. Keeping you safe.”
“My good boy,” Izuku whispered, and sealed his mouth over Katsuki’s. The kiss wasn’t soft. It was deep and claiming, a messy slide of tongues and shared breath. Izuku could taste the sleep on him, the faint ghost of whiskey, and something uniquely, violently Katsuki. He moaned into it, his body arching, his small tits pressing against Katsuki’s solid chest, his puffy nipples scraping against the hard planes.
When he broke for air, a string of saliva connected them. “Show me,” Izuku breathed, his green eyes glazed. “Not the violence. Show me what you think about when you’re… maintaining your world. When you’re out there in the dark, keeping me for yourself.”
Katsuki’s control snapped. In one brutal, fluid motion, he flipped them, pressing Izuku into the rough wool of the rug. He loomed over him, his huge cock hard and leaking against Izuku’s thigh. “I think about this,” he growled, dipping his head to bite at Izuku’s neck, not hard enough to break skin, but enough to brand. “I think about your taste. The way you get so fucking wet for me, even when you’re asleep. I think about my cock buried in this perfect cunt, knowing no one else will ever feel it.” He rutted against him, the blunt head of his cock catching at Izuku’s entrance, not pushing in, just teasing. “I think about you saying ‘my baby boy’ while you cum on my dick.”
Izuku’s legs fell open, a shameless invitation. His hands clawed at Katsuki’s back. “Yes,” he hissed. “That’s what you protect. Now prove it. Prove I’m yours.” Izuku’s hands tightened in Katsuki’s hair, holding him close. His breath was hot against Katsuki’s mouth. “Tell me something else, baby boy.”
“Anything.”
“Have you ever… fucked anyone else?”
Katsuki went very still. The possessive fever in his eyes flickered, a crack of something else—guilt, maybe. He tried to look away, but Izuku’s grip held him fast. “Once.”
“Once?” Izuku’s voice was a razor. “Who?”
“Some girl. In high school.” Katsuki’s jaw worked. “I was sixteen. It was just once.”
“Why?”
“Because I was a fucking idiot.” Katsuki’s gaze snapped back to his, burning with a desperate honesty. “I thought… I didn’t want to be some lame virgin. I didn’t want to be bad at it for you. For when I finally had you.”
The confession landed like a punch. A white-hot, jealous fire exploded behind Izuku’s ribs. “You let her touch you?” he whispered, his voice trembling with a rage he’d never felt. “You let some little girl put her hands on what’s mine?”
“Mommy—”
“No.” Izuku’s strength surged, a mother’s fury and a lover’s jealousy fused into one. He shoved, twisting his hips, and flipped them. Now he was straddling Katsuki, pinning his wrists to the rug beside his head. The morning light carved the sharp lines of Katsuki’s stunned face. “You’re mine. Every part of you. You killed for me. You bled for me. And you gave your first time to some… extra?”
Katsuki stared up at him, his chest heaving. His huge cock lay thick and leaking against his stomach. “It meant nothing,” he rasped. “I couldn’t even finish. All I could think about was you.”
“It should have been me.” Izuku’s voice broke. He reached between his own legs, his fingers slick with his own wetness, and guided Katsuki’s cock to his entrance. He didn’t sink down. He held it there, the blunt head pressing, stretching him just a fraction. “This should have been mine. Your first kiss. Your first touch. Your first everything. You’re my little boy.”
“I am,” Katsuki groaned, his hips bucking up instinctively, seeking the heat. “I’m yours. Fuck, Mommy, please—”
Izuku sank down. He took him in one rough, unforgiving drop, sheathing every thick inch inside himself with a choked cry. The stretch was brutal, perfect. He braced his hands on Katsuki’s chest, his nails biting into the scarred skin. “You don’t get to give anything away ever again,” he panted, already moving, riding him with a furious, grinding rhythm. “You understand me? Everything you are belongs to me.”
“Yes!” Katsuki’s head slammed back against the rug. His hands flew to Izuku’s hips, fingers digging into the soft flesh of his thighs, trying to guide the pace, but Izuku slapped them away.
“No. You don’t move. You took what wasn’t yours to give. Now you take what I give you.” Izuku rode him harder, each downward slam a punishment and a claim. The wet, filthy sound of their joining filled the dusty study. Izuku’s small tits bounced, his puffy nipples tight and aching. “You think about her now? While I’m ruining this perfect cunt for anyone but you?”
“Never—god, never—” Katsuki was trembling, his muscles corded with the effort of staying still. His eyes were wild, worshipful. “Only you. It’s always only been you.”
“Good.” Izuku leaned forward, his curls brushing Katsuki’s face. He captured his mouth in a biting kiss. “My violent, jealous, perfect boy. Mine.” He rode him faster, his own orgasm coiling tight, sparked by jealousy and a dark, total possession. “You’re going to come inside me. You’re going to fill up what’s yours. And you’re never going to think about anyone else.”
Katsuki’s control shattered. A broken, ragged shout tore from his throat as his hips pistoned upward, driving deeper than Izuku could take. His release was a hot, pulsing flood, and Izuku cried out, his own climax ripping through him, squirting on his boy, milking every drop from Katsuki as he chanted “my boy, my boy, mine,” against his sweating skin.
They collapsed together, a shuddering, sticky heap on the rug. Katsuki’s arms locked around Izuku, crushing him close, his face buried in his neck. His breath came in ragged, awestruck pants. “I didn’t know,” he mumbled against his skin, voice thick with something like reverence. “I didn’t know you could be like this.”
Izuku nuzzled into him, the fury spent, leaving a deep, satiated calm. He kissed the sweat-salted hollow of Katsuki’s throat. “You have no idea what I am when someone tries to take what’s mine.”
Katsuki rolled them, a slow, possessive twist of his hips that kept his cock buried deep inside Izuku as their positions reversed. He loomed over him again, casting a shadow that swallowed the morning light. "Again," he whispered, raw and rough against Izuku's mouth.
"Insatiable boy," Izuku breathed, but his legs were already wrapping around Katsuki's waist, heels digging into the small of his back. He was still stretched and tender, still wet with both their releases.
"You made me this way." Katsuki began to move, a slow, grinding roll of his hips that drew a shaky moan from Izuku's throat. It wasn't the punishing pace from before. This was deliberate, deep, a reclaiming of the rhythm. "Hearing you like that… seeing you claim me like that… fuck, Mommy. You ruin me."
Izuku's hands came up to frame Katsuki's face. His thumbs brushed over the sharp cheekbones, smearing away a tear of sweat. "You liked it? Me being jealous? Me punishing you for giving away a piece of what's mine?"
"Liked it?" Katsuki's hips stuttered. He drove in harder, making Izuku gasp. "I've never come that hard in my life. I'd dig up that girl and kill her again if it meant you'd look at me like that one more time."
A shocked, breathless laugh escaped Izuku. It was horrifying. It was the most romantic thing he'd ever heard. He pulled Katsuki down into a searing kiss. "You're perfect," he mumbled against his lips. "My perfect, monstrous boy. All mine."
"Say it," Katsuki grunted, his pace increasing, the wet slap of skin echoing in the quiet room. His cock dragged over that deep, sensitive spot inside with every thrust. "Tell me who I belong to."
"You belong to me, Kacchan. Only me." Izuku's head tipped back, his curls flattening against the rug. His eyes were glazed, unfocused with pleasure. "Your body is mine. Your past is mine. Your sins are mine. I own all of it."
"Yeah," Katsuki choked out. His control was fraying again, his thrusts turning ragged. "God, yes. Take it. Take everything."
Izuku could feel the heat coiling again, tighter and brighter this time. It wasn't fueled by fury now, but by a devastating, all-consuming rightness. This was where he was meant to be. Under his son. Filled by him. Claimed by him. "Inside," he pleaded, his nails scoring down Katsuki's back. "I want to feel you. I want to carry you all day."
Katsuki's answer was a broken groan. He buried his face in Izuku's neck, his hips losing all rhythm as he emptied himself with a series of deep, pulsing spurts. The heat was a brand. Izuku cried out, his own release washing through him in a weaker, shimmering wave, his pussy fluttering and milking Katsuki's cock through the last of his climax.
They lay like that for a long time, Katsuki's weight a welcome anchor, his softening cock still nestled inside. Izuku traced idle patterns over the scars on Katsuki's shoulders. "You'll tell me," he said softly, not a question. "From now on. If you get hurt. Even a scratch."
Katsuki turned his head, his lips brushing Izuku's jaw. "You'll tell me," he echoed, "if anyone looks at you. Even for a second."
Izuku smiled, a small, dark curve of his lips. "It's a deal, baby boy."