I never planned on banging my trans sister, but there we were, the night it all went down. Mom and dad were out of town, and I walked into her room to borrow a charger. There she was, Lena, 22, naked on the bed, her thick cock in one hand, stroking slow and hard while she watched some porn on her phone. Her tits were small and perky, nipples hard, and that dick of hers was seven inches of veiny meat, leaking precum onto her stomach. She didn't even flinch when she saw me.
"Shut the door, Jake," she said, voice low and dirty. "Or get the fuck out."
I shut the door. My own cock was already straining against my jeans. We'd always been close, but this was different. Lena had come out as trans a couple years back, started hormones, kept her cock because she liked it that way. I'd jerked off thinking about it more times than I could count. Now here it was, real.
She spread her legs wider, showing off her smooth balls and the tight pucker of her ass. "You like what you see, little brother? Come suck your sister's cock."
I dropped to my knees at the edge of the bed. No hesitation. I grabbed her shaft, warm and pulsing in my hand, and licked the head, tasting that salty precum. Lena moaned and pushed her hips up. I took her deep, lips stretching around her girth, tongue working the underside while I bobbed. She tasted good, musky and sweet from the lube she'd used. My hand cupped her balls, rolling them as I sucked harder.
"Fuck yeah, suck it," she growled, grabbing my hair. "You've wanted this, haven't you? Your trans sister's dick down your throat."
I pulled off just long enough to say, "Yeah, Lena. Want to fuck you too." Then I went back down, gagging a little when she thrust up. Spit ran down her shaft onto her balls. She was rock hard now, veins throbbing against my tongue.
She pulled me up after a minute. "Strip. Get on the bed."
I yanked off my clothes. My cock sprang free, eight inches and leaking. Lena pushed me onto my back and straddled my chest, feeding me her cock again while she reached back and stroked mine. Her hand was firm, twisting on the upstroke. Then she shifted, turning around so her ass was over my face. I spread her cheeks and buried my tongue in her hole, licking and spitting while she sucked my dick.
We 69'd like that for a while, sloppy and loud. Her mouth was wet heat, taking me to the root. I tongue-fucked her ass until it was slick and open. She pulled off my cock with a pop.
"Want to fuck your sister's ass, Jake? Been dreaming about pounding this trans pussy?"
I flipped her onto her stomach, grabbed the lube from her nightstand, and slicked my cock. I pressed the head against her hole and pushed in slow. She was tight, gripping me like a fist. Lena groaned into the pillow as I sank balls-deep.
"Fuck me hard," she demanded. "Don't hold back."
I started thrusting, deep and rough. Her ass cheeks slapped against my hips. I reached under and grabbed her cock, jerking it in time with my strokes. Precum dripped from her onto the sheets. She pushed back, meeting every thrust, moaning filthy shit about how good her brother's cock felt in her trans ass.
We switched positions. She got on all fours and I pounded her from behind, one hand on her hip, the other reaching around to stroke her cock. She came first, shooting thick ropes onto the bed while her ass clenched around me. That pushed me over. I buried deep and unloaded, pumping cum into her hole until it leaked out around my shaft.
We didn't stop there. She rode me next, her cock slapping against my stomach as she bounced. Then I fucked her on her back, legs over my shoulders, watching her face while I drilled her. We swapped again, her on top, grinding her ass on my dick while I sucked her tits and jerked her off until she came on my chest.
By the end we were both spent, covered in sweat and cum, breathing hard. Lena kissed me, tongue deep, then whispered, "This is our secret, brother. But we're doing it again."
I nodded, already hard again at the thought. Our first time was just the start of the dirtiest family secret we'd ever keep.