We were both adults when it started, me twenty-four and her twenty-one, but that didn't stop the filthy need from hitting us like a truck the night our parents left for the week. She walked into the kitchen in nothing but a thin tank top and panties, nipples poking hard, and I knew right then I was going to fuck her and put a baby in her.
"Stop staring, big brother," she said, but her voice was already thick and her eyes dropped to the bulge in my shorts. I didn't stop. I grabbed her hips, spun her around, and bent her over the counter.
"You want this cock?" I growled, yanking her panties down. Her pussy was already dripping, slick and swollen. "Tell me you want me to breed you."
She moaned and pushed back. "Fuck yes. Shove it in. Fill me up. I want your cum deep so it sticks."
I didn't tease. I lined up my thick cock and slammed inside in one thrust. Her tight cunt gripped me like a fist, hot and wet, sucking me in. I fucked her hard right there, hips slapping against her ass, the wet sounds of her pussy taking every inch filling the room. She clawed the counter and begged.
"Harder. Pound my cunt. Make me take every drop. Breed your little sister."
I reached around and rubbed her clit while I drove into her. Her walls fluttered and she came fast, squirting around my cock, but I didn't stop. I kept railing her, balls slapping, until I felt that familiar tightening. I buried myself to the hilt and unloaded, pumping thick ropes of cum straight into her womb. She pushed back, milking me, moaning like a whore about how she could feel it flooding her.
We didn't leave the house much that week. Every morning I woke her by sliding into her from behind while she was still half-asleep, pumping her full before breakfast. She walked around the house leaking my cum down her thighs, wearing nothing but my shirts. At lunch I bent her over the dining table and fucked her doggy style, telling her exactly what I was doing.
"Take it deep. I'm gonna knock you up. Your belly's gonna swell with my kid and everyone will know your brother bred you."
She came screaming every time, begging for more. One afternoon I had her ride me on the couch, her tits bouncing in my face while she ground down, taking me balls-deep. I sucked her nipples and told her they'd be leaking milk soon. She clenched hard around me and came again, then I flipped her onto her back, legs over my shoulders, and fucked her in long, punishing strokes until I flooded her again.
By the fourth day she was insatiable. She woke me with her mouth around my cock, sucking greedily, then climbed on and sank down, riding me reverse so I could watch her ass bounce. "Cum in me again," she panted. "I want to be pregnant so bad. Your cum feels so good inside me."
I grabbed her hips and thrust up, shooting another heavy load while she rubbed her clit and came with me. We stayed locked together afterward, my cock still twitching inside her, keeping every drop where it belonged.
On the last night before our parents came home I took her to the bedroom and fucked her slow and deep for hours. Missionary, her legs wrapped around me, my mouth on hers while I whispered how full her pussy was with my seed. She came twice before I finally let go, grinding in as I pumped what felt like the biggest load yet straight against her cervix.
When we finally collapsed she kept her hips tilted up, holding my cum inside. "Think it took?" she whispered, fingers tracing her lower belly.
I slid two fingers into her sloppy cunt and pushed the leaking cum back in. "If it didn't, we'll keep trying until it does."
She smiled and pulled me in for another kiss. We both knew this was only the beginning.
