Mark slammed the front door behind him and dropped his keys on the table. At 24 he was already hard just thinking about his sister Emily getting home from her shift. She was 21 now, legal in every way that mattered, but the fact she was his little sister made his cock throb harder every time. He heard the shower running upstairs and grinned. No more pretending.
He climbed the stairs two at a time, stripped his shirt off, and pushed the bathroom door open. Emily stood naked under the spray, water running down her full tits and over the shaved slit between her legs. She looked up, eyes wide for a second, then smirked.
"Took you long enough, big brother," she said, voice already husky. "Get in here and fuck me."
Mark shoved his jeans down. His thick cock sprang out, already leaking. He stepped into the shower, grabbed her by the hips, and spun her around. "Bend over. Hands on the wall."
Emily obeyed, arching her back so her ass pushed out. Mark didn't tease. He lined up and drove his cock straight into her tight pussy in one hard thrust. She moaned loud, the sound echoing off the tiles.
"Fuck yes," she gasped. "Deeper. Wreck your sister's cunt."
He slammed into her again and again, balls slapping against her. Water splashed everywhere. His hands gripped her hips hard enough to leave marks while he pounded her. Emily pushed back to meet every thrust, her pussy clenching around him.
"Talk dirty to me," he growled.
"Your cock feels so fucking good in me," she panted. "I've been wet all day thinking about my brother stretching me open. Cum in me, Mark. Fill your sister's hole."
He reached around and rubbed her clit fast and rough. Emily came hard, legs shaking, pussy pulsing and squeezing his shaft. The feel of it pushed him over. He buried himself to the hilt and shot rope after rope of thick cum deep inside her.
They stayed locked together, breathing hard, hot water still pouring over them. Mark didn't pull out. He stayed buried in her, cock twitching as her walls milked the last drops.
"Shower's not over yet," Emily said, turning her head to kiss him messy and open-mouthed. "Take me to bed. I want you to fuck my ass next."
Mark pulled out, spun her, and lifted her up. Her legs wrapped around his waist as he carried her dripping wet down the hall. He dropped her on her bed and flipped her onto her stomach again. This time he spread her cheeks and pressed his still-hard cock against her tight asshole, using their mixed cum as lube.
He pushed in slow but steady until he was balls deep in her ass. Emily groaned into the pillow, pushing back for more.
"Goddamn, you're so fucking tight," he grunted, starting to thrust. "My sister's ass was made for my cock."
He fucked her harder, reaching under to finger her cum-filled pussy at the same time. Emily came again, screaming his name. Mark followed soon after, pumping another load into her ass.
They collapsed side by side, sweaty and satisfied. Emily reached down and stroked his softening cock, already coaxing it back to life.
"Round three in ten minutes," she whispered. "I want you to eat my pussy while I suck you off. Then you can fuck me however you want all night."
Mark grinned against her neck. "Anything for my dirty little sister."
They spent the rest of the night exactly like that—raw, filthy, and completely addicted to each other. No guilt. Just two adults who finally stopped pretending they didn't want exactly this.
