Katsuki’s stillness broke. He rolled Izuku beneath him, the sleeping bag bunching under their combined weight, his eyes dark with a terrifying finality. He didn’t speak. He just pushed in, a slow, deep invasion that stole the air from Izuku’s lungs.

His thrusts weren’t frantic. They were deliberate. Measured. Each one drove deeper than the last, a brutal, claiming rhythm that felt less like sex and more like a brand being seared into Izuku’s soul.

“Dad—” Izuku sobbed, his head pressing back into the padded floor of the tent.

“Look at me.” Katsuki’s voice was gravel, low and unyielding. His hips never stopped their punishing pace.

Izuku forced his eyes open. His father’s face was above him, sheened in sweat, every muscle in his neck corded with strain. The summer storm in his eyes was a fixed, raging point.

“You feel that?” Katsuki grunted, punctuating the question with a thrust that made Izuku cry out. “That’s me. Everywhere. That’s who you belong to.”

“I know,” Izuku gasped, his own hands scrambling against Katsuki’s back, fingernails biting into sun-warmed skin. “I know, I know—”

“Say it.”

“I’m yours.” The words were a broken whisper, then a scream as Katsuki angled himself, hitting a place that lit Izuku’s nerves on fire. “I’m yours!”

Katsuki’s control was a violent, living thing. He braced one hand by Izuku’s head, the other gripping his hip hard enough to bruise, holding him open, forcing him to take every inch. The wet, slick sound of their joining filled the hot, trapped air. Izuku could smell them—pine soap and sweat and the raw, musky scent of his own arousal.

“Never gonna be clean of this,” Katsuki breathed, the words hot against Izuku’s mouth. “Never gonna be right. You understand that? This is it.”

Izuku could only nod, his vision blurring. He wrapped his legs around Katsuki’s waist, heels digging into the small of his back, pulling him closer, taking him deeper. It was an acceptance. A surrender. A plea for more.

Katsuki watched him break apart beneath him, his thrusts deepening, slowing, becoming even more devastating. “Mine,” he growled, a final, quiet vow into the space between them.

"Come inside me," Izuku gasped, the words tearing from his throat raw. He clutched at Katsuki's shoulders, his blunt nails digging in. "Please, Daddy. Please, I need it. Need you to—"

"I know what you need." Katsuki’s voice was a low rasp, his rhythm unbreaking, each deep thrust punching the air from Izuku’s lungs. His eyes were fixed, unblinking, on his son’s face. "You want me to fill you up? Mark you from the inside?"

"Yes." Izuku sobbed, his hips straining up to meet every punishing drive. "I want it. I want everything."

"Greedy." Katsuki’s hand slid from Izuku’s hip to his ass, gripping the soft flesh, spreading him wider. The wet, rhythmic sound of their bodies connecting grew louder, obscene in the close heat. "My greedy boy."

Izuku could feel the tension coiling in Katsuki’s lower back, the faint, telltale jerk in his thrusts that meant he was close. The anticipation was a live wire under Izuku’s skin. "Do it. I’m yours. Let everyone know."

Katsuki’s breath hitched. A low, guttural sound escaped him, part growl, part surrender. His pace lost its brutal precision, turning frantic, desperate. He buried his face against Izuku’s neck, his teeth scraping the sweat-damp skin.

"Now," Izuku begged, his own climax clawing its way up his spine, triggered by the feel of Katsuki unraveling above him. "Please, now, Daddy—"

Katsuki went rigid. A sharp, broken groan was muffled against Izuku’s throat. Izuku felt it—the hot, pulsing rush deep inside him, a flood of possession that made his own body seize. He came with a choked cry, his back arching off the tent floor, his pussy clenching rhythmically around Katsuki’s still-spurting cock.

For a long moment, there was only the sound of their ragged breathing and the wet, intimate seep of Katsuki’s release inside him. Katsuki didn’t pull out. His weight was a crushing, perfect anchor.

"Feel that?" Katsuki muttered, his lips moving against Izuku’s pulse point. His hips gave one last, shallow roll, pressing his spend deeper.

Izuku nodded, dazed. He could feel it. A warm, leaking proof. "I feel it."

Katsuki finally lifted his head. His red eyes were dark, exhausted, stripped bare. He looked down at where their bodies were joined. "There’s no going back from that."

"I don’t want to go back." Izuku’s voice was soft, wrecked. He brought a trembling hand up to touch his father’s jaw. "I want to stay right here. Ruined. With you."

Katsuki caught his wrist, not to push it away, but to hold it there. He turned his face into Izuku’s palm, inhaling sharply. When he spoke, the words were so quiet they were almost lost in the nylon rustle of the tent. "What have we done?"

It wasn’t a question for Izuku to answer. It was a confession. Izuku just pulled him down, wrapping his arms around Katsuki’s neck, holding him inside, holding him close, as if he could keep the world from finding the brand they’d just made.

Katsuki kissed him.

It wasn't the hard, claiming pressure from before. His mouth was soft, a slow, devastating tenderness that made Izuku’s breath catch. He tasted like salt and sweat and something uniquely, intimately his father. The kiss lingered, a quiet seal over the violent brand he’d just left.

The kiss broke. Their breath mixed in the scant inch between their mouths. Izuku’s heart was a frantic drum against his ribs, echoing where their bodies were still joined. “What are we?” he whispered, the question he’d been holding for a thousand miles finally set free in the humid dark.

Katsuki didn’t move. He stayed buried inside him, a heavy, warm presence. His eyes searched Izuku’s face. “What do you think we are?”

“I asked you first.” Izuku’s voice was small, but it didn’t waver. His fingers traced the line of Katsuki’s shoulder. “You just… you came inside me. Again. After everything. So what does that make this?”

“It makes it a mess.” Katsuki’s words were flat. He finally shifted, pulling out slowly. Izuku gasped at the sudden emptiness, the wet, hot trickle that followed. Katsuki rolled onto his back beside him, one arm thrown over his eyes. “A goddamn catastrophe.”

“That’s not an answer.” Izuku propped himself up on an elbow, looking down at his father’s profile. The rigid set of his jaw. “A catastrophe is an event. This is… we’re something. Aren’t we?”

Katsuki was silent for a long moment. The tent held its breath. “Lovers.” The word came out choked, like it cut his throat on the way up. He laughed, a harsh, broken sound. “Jesus Christ. I’m fucking my son. We’re lovers.”

Izuku flinched like he’d been slapped. The tears came fast, hot and silent, spilling over his freckled cheeks and into the damp green curls at his temples. He turned his face away, a choked sob catching in his throat.

“Don’t,” Katsuki said, the word rough. He didn’t move his arm from his eyes.

“Don’t what?” Izuku’s voice was a wet, shattered thing. “Don’t cry because you sound like you hate it? Hate me?”

“I don’t hate you.”

“You sound like you do!” Izuku pushed himself up fully, the sleeping bag sticking to his sweaty back. He swiped at his face angrily, but the tears kept coming. “You say it like it’s a disease. ‘Lovers.’ Like it’s the worst thing you’ve ever had to say.”

Katsuki finally lowered his arm. His red eyes were bloodshot, exhausted. He looked at Izuku’s heaving shoulders, the tear-tracks gleaming in the dim light. “It is.”

Izuku let out a broken laugh. “Then why? Why do you keep… why did you just…” He gestured weakly between his own spread legs, at the evidence cooling on his inner thighs.

“Because I’m sick, too.” Katsuki pushed himself up to sit, the muscles in his abdomen flexing. He reached out, his calloused thumb catching a tear on Izuku’s cheek. His touch was incongruously gentle. “It’s a sickness, Izuku. And I’m letting us both drown in it.”

The slap cracked through the humid air of the tent, sharp and shocking as a gunshot. Izuku’s palm connected with Katsuki’s cheek with a force that snapped his father’s head to the side. “I’M NOT A SICKNESS!” Izuku screamed, the words tearing from his throat raw and ragged, his chest heaving.

Katsuki slowly turned his face back. A red handprint bloomed across his cheekbone. His red eyes were wide, not with anger, but with a kind of stunned clarity. He didn’t move to retaliate. He just stared.

“You don’t get to say that.” Izuku was trembling, tears of fury now, not sorrow. “You don’t get to fuck me full of your come and then call what we are a disease. I’m not a symptom. I’m a person. I’m your—”

“My son.” Katsuki’s voice was quiet, gravel scraped bare. “You’re my son. That’s the sickness. Not you. The fact that I want you anyway.”

“Then want me!” Izuku shouted, shoving at Katsuki’s bare chest. “Want me without the fucking lecture! Want me without hating yourself after! You just… you claimed me. You branded me. Now own it!”

Katsuki caught his wrists, his grip iron. “I am owning it.” He yanked Izuku forward, their faces inches apart. His breath was hot. “Every time I push inside you, I own it. Every time I fill you up, I own it. The owning is what’s killing me, you stupid boy.”

“It doesn’t look like it’s killing you.” Izuku’s gaze dropped pointedly between their bodies. Katsuki was already hard again, his thick, uncut cock lying heavy and full against his thigh. “It looks like it’s all you want.”

A muscle ticked in Katsuki’s jaw. He released one of Izuku’s wrists to wrap a hand around the back of his neck, holding him in place. “It is.” He leaned in, his lips brushing Izuku’s ear. “That’s the hell of it. I want my son’s tight little cunt more than I’ve wanted anything in my whole, godforsaken life. You feel that?” He ground his erection against Izuku’s sticky thigh. “That’s how sick I am for you.”

Izuku shuddered, a fresh wave of heat pooling low in his belly. The crude words, the possessive grip, the undeniable proof of Katsuki’s arousal—it unspooled his anger, leaving only a desperate, aching want.

"No." Izuku's voice was a ragged whisper. He was trembling, his thighs slick where Katsuki's cock pressed, but he shook his head. "I can't. I can't keep doing this."

Katsuki went still, his hand a heavy brand on the back of Izuku's neck. "What?"

"This." Izuku pushed against his chest, a weak shove that gained him an inch of space. The air between them felt charged, brittle. "If you're not going to… to really love me. If you aren't going to choose me over her, over everything… then you need to stop. Because I can't." A fresh tear traced his cheek. "I just keep falling more in love with you. And this… the fucking… without the other part? It's starting to hurt too much."

Katsuki released him. He leaned back, his expression unreadable. His erection hadn't flagged; it jutted against his stomach, a blatant contradiction to the words hanging in the air. "You want me to choose you."

"I want you to want to!" Izuku wrapped his arms around himself, feeling exposed, the come on his thighs cooling. "I don't care that you're my father. I care that you look at me like I'm a mistake you can't stop making. I need more than just stolen moments in tents. More than just your… your sick want."

"There is no more." Katsuki's voice was low, final. "This is the more. This filth. This sin. This is all there is for us."

"Choose," Izuku said, his voice stripped raw. The word hung between them, a blade. "Her or me. You don't get to have both anymore. Not after this."

Katsuki stared at him. The red handprint on his cheek stood out like a fresh brand. "You're asking me to destroy my life."

"You already did!" Izuku's laugh was broken glass. "The second you kissed me back. The second you put your cock in me. You already chose. You're just too much of a coward to admit it out loud."

"I'm a coward?" Katsuki leaned forward, his face inches from Izuku's. The heat of him was suffocating. "I'm the one living in this fucking tent with you. I'm the one who answers my wife's calls with my dick buried in my son. What part of that screams 'coward' to you?"

"The part where you still call her your wife!" Izuku shouted. "The part where you look at me like I'm ruin instead of... instead of..." He choked, the rest of the sentence dying.

"Instead of what?" Katsuki's voice dropped to a dangerous rasp. "Your lover? Your boyfriend? Your fucking soulmate? Pick a fairytale, Izuku. None of them fit."

"Then make one that does!" Tears streamed down Izuku's face, cutting through the sweat and drying come. "Stop acting like this is something that's happening to you. You're doing it. You want it. I can feel how much you want it." His eyes dropped to Katsuki's rigid cock, which jumped at the attention. "So choose. Right now. My mother or me."

Katsuki didn't speak. The silence in the tent thickened, a living thing. He looked at Izuku—at his trembling mouth, his heaving chest, the mess between his thighs—and something in his stormy eyes shattered. The calculated distance evaporated. What was left was pure, terrifying want.

"You," he breathed, the word a surrender and a condemnation. "It's always been you. Even when it couldn't be. Even when I didn't know."

Izuku sobbed, a ragged sound of relief and heartbreak. "Say it again."

"You." Katsuki reached for him, his big hand cradling Izuku's jaw. His thumb brushed over his lower lip. "I choose you, you impossible, heartbreaking boy. I burn it all down for you."

Then he kissed him. It wasn't gentle. It was a claiming of a different kind—desperate, hungry, wet with salt from both their tears. Izuku melted into it, his hands fisting in Katsuki's hair, pulling him closer, trying to crawl inside his skin.

Katsuki broke the kiss, his breathing harsh. "But you get all of it. You understand? The sin. The filth. The fucking horror of what we are. You don't just get the parts that feel good. You get the monster, too." He pushed Izuku down onto the rumpled sleeping bag, his weight a delicious, familiar anchor.

"I want the monster," Izuku gasped, spreading his legs. His pussy was already slick, aching, clenching around nothing. "I want everything."

Katsuki looked down at him, his expression terrifyingly solemn. He positioned himself, the broad, leaking head of his cock nudging against Izuku's soaked entrance. "This is me choosing you," he said, his voice low and final. He didn't push forward. He held them there, at the threshold, making Izuku feel the promise and the threat of it. "Every inch. Every time. It's yours."