The house was empty except for us. Mom and Dad had left for the weekend, and the second the door shut behind their car, the air between me and my sister changed. Sarah was twenty-two, two years older than me, and she had been walking around in nothing but a thin tank top and panties all afternoon. Her tits pressed against the cotton, nipples hard, and every time she bent over I got a full view of her round ass.
I tried to ignore it. I sat on the couch scrolling my phone while she stood in the kitchen making a snack. But she kept glancing over, biting her lip like she knew exactly what she was doing.
"You keep staring," she said finally, voice low and teasing. "You want to fuck me, don't you?"
The words hit like a punch. My cock twitched instantly in my shorts. "Sarah, that's fucked up."
She walked over, hips swaying, and stopped right in front of me. "So what? It's just us. No one has to know." She reached down and grabbed my dick through the fabric. It was already rock hard. "Jesus, you're throbbing. You've been thinking about this too."
I should have pushed her away. Instead I grabbed her wrist and pulled her onto my lap. Her ass settled right over my bulge and she ground down, slow and dirty. "Tell me you don't want to shove this cock in your big sister's pussy," she whispered against my ear.
"Fuck," I groaned. My hands slid under her tank top and I squeezed her tits, thumbs rubbing those stiff nipples. She moaned and rocked harder. "You're soaked already.
I can feel it through your panties."
She reached between us, yanked my shorts down, and wrapped her fingers around my shaft. "It's bigger than I thought. Thick. I want it stretching me." She stood up just long enough to peel off her panties, then climbed back on, straddling me. Her pussy was shaved smooth and dripping. She rubbed her wet slit along the head of my cock, coating it.
I thrust up without thinking and the tip pushed inside her. She was tight, hot, and she sank down in one slow motion until I was buried balls-deep. "Oh my God," she gasped. "My brother's cock is inside me. Fuck, that feels so wrong and so good."
She started riding me hard, tits bouncing, ass slapping against my thighs. I grabbed her hips and slammed up to meet every drop. The wet sounds filled the living room. "You like that, you dirty slut?" I growled. "Fucking your little brother like a whore."
"Yes," she hissed. "Deeper. Wreck my cunt." She leaned forward and kissed me, tongue messy, teeth nipping. I reached around and smacked her ass, then spread her cheeks and pushed a finger against her asshole while I fucked her. She clenched around me and came with a sharp cry, pussy pulsing and gushing.
I didn't stop. I flipped her onto her back on the couch, hooked her legs over my shoulders, and pounded her. Her tits shook with every thrust. "Fill me up," she begged. "Come inside your sister. I want to feel it leaking out of me."
I lost it. I buried myself to the hilt and shot deep, pulse after pulse of thick cum flooding her. She kept squeezing me, milking every drop, moaning like she couldn't get enough.
We didn't stop there. An hour later she was on her knees in the shower, sucking my cock clean while hot water ran over us. She took me down her throat until I was hard again, then turned around and begged me to fuck her ass. I did, slow at first, then rough, her hands braced against the tiles while she fingered her own pussy.
By the time the weekend ended we had fucked in every room. On the kitchen counter, bent over the dining table, in Mom and Dad's bed with her screaming my name. Every time it got dirtier. She made me call her "sis" while I came. I made her beg for my load in her mouth, on her tits, deep in her ass.
When our parents' car pulled into the driveway Sunday night, Sarah was still full of my cum. She kissed my cheek like nothing had happened, but her eyes promised more the next time we were alone.
We never talked about stopping. We just kept going, quiet and filthy, every chance we got.
