The house was dead quiet when Mark got home from the bar. He was twenty-four, drunk, and hard as fuck after watching his buddies talk about their latest lays. His little sister Lisa, twenty and home from college for the weekend, was the only one there. She was in the kitchen in tiny shorts and a tank top, bending over to grab a soda from the fridge. Her ass cheeks peeked out, round and smooth, and Mark felt his cock twitch.
He didn't think. He just moved. One hand clamped over her mouth, the other yanking her back against him so she could feel his thick dick pressing into her ass. "Don't fucking scream," he growled in her ear. "It's just us. Mom and Dad are gone till Monday."
Lisa's eyes went wide. She tried to twist away, but Mark was bigger, stronger. He spun her around, shoved her against the counter, and ripped her tank top down. Her tits spilled out, nipples already tight from the shock. "Mark, what the hell—stop!" she hissed, but her voice cracked.
He laughed low and dirty. "You've been teasing me for years in those slutty clothes. Tonight you're taking this cock whether you like it or not." He forced her shorts and panties down in one rough tug. Her pussy was bare, pink, and when he shoved two fingers between her legs she was wetter than she wanted to admit. "Look at that. Your cunt's dripping for your own brother."
Lisa struggled, slapping at his chest, but Mark pinned her wrists above her head with one hand and used the other to free his cock. It was long, veined, and already leaking. He rubbed the fat head up and down her slit, coating it in her juices. "Beg me to stop and I'll just fuck you harder," he warned, then slammed inside her in one brutal thrust.
She cried out, body stretching around him. Mark didn't give her time to adjust. He pounded into her, hips slapping loud against her ass, the wet sounds of forced incest filling the kitchen. "Fuck, your pussy's tight," he grunted. "Better than any girl I've had. You were made for your brother's dick."
Lisa's protests turned into broken moans even as she tried to push him off. Her walls clenched around him, betraying her. Mark reached down and rubbed her clit in fast circles. "Come on it. Come on your brother's cock while I take what I want."
Her orgasm hit hard, legs shaking, a gush of wetness soaking his balls. Mark kept fucking her through it, then pulled out and spun her around. He bent her over the counter, kicked her legs apart, and drove back in from behind. One hand fisted her hair, yanking her head back. "Say it," he demanded. "Say you want your brother's cum."
"No—fuck you," she gasped, but her hips pushed back to meet his thrusts.
He slapped her ass hard, leaving a red handprint. "Wrong answer." Mark fucked her faster, balls slapping, the slap of skin on skin echoing. He reached around and pinched her nipples, twisting just enough to make her whimper.
"This is free forced incest sex, sis. You're getting it raw and you're gonna take every drop."
Lisa came again, harder this time, her pussy milking him. Mark roared and buried himself deep, flooding her with thick ropes of cum. He kept pumping, making sure it stayed inside, marking her as his. When he finally pulled out, cum leaked down her thighs.
He didn't let her rest. Mark dragged her to the living room couch, pushed her down on all fours, and shoved back inside her cum-slick hole. "Round two," he said, voice rough. "Gonna fuck this ass next if you keep fighting."
By the third round on her bed, Lisa was limp and moaning, no longer pushing him away. Mark held her down, legs over his shoulders, pounding deep while he told her exactly how her pussy belonged to him now. "Every time you're home, this cunt's mine. Forced or not, you're gonna come for your brother."
He filled her again, then made her suck him clean, his cock tasting like their mixed cum. Lisa's eyes were glassy, body marked with his bites and handprints. Mark pulled her close after, still inside her, and whispered against her ear, "This is just the start of our free forced incest sex storie."
They stayed tangled like that until morning, his cum still dripping from her well-used holes.
