I slammed the door behind me after another bullshit family dinner, but my stepsister Lena was already waiting in the hallway, arms crossed under those heavy tits that always strained her tank tops. She was twenty-one, same as me, both of us home from college for the summer, and the tension had been building since the first night we got back. Mom and Dad were downstairs finishing their wine, clueless as usual.
"You've been staring at my ass all night," she said, voice low and filthy. "Don't think I didn't notice."
I didn't deny it. "So what if I was? That skirt's so short it's basically an invitation."
Lena stepped closer, pressing her body against mine until I could feel the heat coming off her. "Then stop talking and do something about it. Fuck me from behind like you've been dying to."
We didn't make it to the bedroom. She grabbed my hand and dragged me into the guest bathroom at the end of the hall, locking the door behind us. The second it clicked she bent over the sink, yanking her skirt up to her waist. No panties. Just smooth, round cheeks and a shaved pussy already glistening.
I dropped my pants fast, cock springing out hard and ready. No foreplay, no sweet shit. She wanted it raw. I grabbed her hips, lined up, and shoved in deep in one thrust. Lena moaned loud, biting her arm to stay quiet while I started pounding her from behind.
Her walls gripped me tight, wet and hot, every slam of my hips making her ass ripple. I reached around and rubbed her clit hard with two fingers, feeling her juices coat my hand. "This what you wanted, sis? Your brother fucking you stupid in the bathroom?"
"Yes," she hissed, pushing back to meet every thrust. "Harder. Make it hurt."
I gave her what she asked for, slamming so deep my balls slapped her clit with every stroke. The mirror showed her face twisted in pleasure, mouth open, eyes half-lidded. I grabbed a fistful of her hair and pulled, arching her back so I could go even deeper. Her pussy clenched around me every time I bottomed out.
We heard footsteps on the stairs. Mom calling our names. We didn't stop. Lena reached back and spread her ass wider, giving me a perfect view of my cock disappearing into her soaked hole. "Don't you dare pull out," she whispered. "Fill me up."
I fucked her faster, the wet sounds of skin on skin filling the small room. My balls tightened, pressure building fast. Lena came first, her whole body shaking, pussy pulsing around my shaft as she bit down on her wrist to muffle the scream. That did it. I buried myself to the hilt and unloaded, pumping thick ropes of cum deep inside her while she milked every drop.
We stayed locked together for a minute, breathing hard, my cum already starting to leak out around my cock. Then she straightened up, pulled her skirt down like nothing happened, and smirked at me in the mirror.
"Round two after they go to bed," she said, unlocking the door. "This time on the kitchen table. From behind, just like you like it."
I was already hard again before she left the room.
