I never meant for it to happen, but once it started I couldn't stop. I'm 24 now and my sister Emma is 22. We grew up close, always sharing everything, but last summer when she moved back home after college we crossed the line for good.
It was late one night. Mom and Dad were asleep downstairs. Emma came into my room wearing just a thin tank top and panties, complaining about the heat. She climbed into my bed like she used to when we were kids, but this time her body pressed against mine differently. Her ass brushed my cock and I got hard instantly. She felt it and froze for a second, then pushed back harder.
"Fuck, you're really hard," she whispered.
I didn't answer with words. I slid my hand between her legs and found her pussy already wet through the cotton. She moaned low and spread for me. I yanked her panties aside and sank two fingers straight into her tight cunt. She was dripping, hot, and she started riding my hand right there.
We didn't talk about it being wrong. We just needed it. I pulled my shorts down and she wrapped her fingers around my cock, stroking me slow and firm. "Put it in me," she said. "I want you to cum in my pussy."
I rolled her onto her back, pushed her knees up, and drove my cock balls-deep in one thrust. Her pussy gripped me like it was made for it. She was so wet the sounds were filthy, slick and loud every time I slammed in. I fucked her hard, no holding back, the bed creaking under us. Emma bit the pillow to stay quiet but her moans still slipped out.
I lasted longer than I thought I would. She came first, her pussy pulsing and squeezing around my shaft, juices running down my balls. That pushed me over. I buried myself as deep as I could and unloaded, pumping thick ropes of cum straight into her cunt. I kept thrusting through it, making sure every drop stayed inside her.
After that night we couldn't get enough. Every chance we got we fucked. In the shower, in the garage, once even in the backyard at night. She loved it when I filled her up and she'd walk around with my cum leaking down her thighs. Sometimes she'd sit on my lap on the couch while our parents watched TV, my cock buried in her pussy under a blanket, slowly grinding until I came inside her again.
The Tumblr posts started as a way to remember. She made an anonymous account and wrote out every detail. People ate it up. The more comments she got calling it hot, the dirtier she got with me. One afternoon she showed me a new post while I was balls-deep in her from behind.
"Read it while you fuck me," she said.
The story described exactly what we were doing: how she begged for my cum in her pussy, how she loved feeling it drip out later, how we both knew it was wrong but couldn't stop. I read the words out loud while I pounded her, and when I finished she came so hard she shook.
We kept going for months. Missionary, doggy, her riding me, me holding her down and breeding her pussy over and over. She got on birth control but we never used condoms. The risk and the taboo made every load better. Sometimes she'd text me from the next room: "Come fill my pussy again."
By the end of that summer we had dozens of stories saved. Each one ended the same way, with me pumping cum deep into her cunt while she begged for more.
We both knew it had to stay secret, but the heat between us only grew. Every time I slid into her it felt like coming home to the one place I wasn't supposed to be, and I never wanted to leave.
