Accidental Sex With My GF’s Sister

I never planned to fuck my girlfriend’s sister. Hell, I never even let myself fantasize about it out loud. But some accidents feel inevitable once the tension has been simmering for months.

My girlfriend, Jessica, was twenty-four, blonde, athletic, and the kind of woman who walked into a room and owned it. Her younger sister, Emily, was twenty-two, a few inches shorter, softer in the curves, with the same bright blue eyes and full lips. They shared a two-bedroom apartment in a quiet complex outside Raleigh. Jessica worked long shifts at the hospital. Emily was finishing her last semester of nursing school and spent most afternoons home alone.

I had a key. Jessica had given it to me months earlier so I could let myself in after work and wait for her. That summer the routine became dangerous. Emily stopped bothering to get fully dressed when she knew I was coming. A thin white tank top with no bra. Tiny cotton panties that rode up between her ass cheeks. Sometimes she answered the door still damp from a shower, hair piled on her head, skin glowing.

I told myself I was loyal. I told myself the ache in my cock every time she stretched across the couch was just biology. I was wrong.

It was a Thursday in late July. Jessica had texted that she was stuck on an overtime shift and wouldn’t be home until after nine. I got off early and drove straight over, still in my work clothes—jeans and a button-down with the sleeves rolled up. The afternoon heat pressed against the windows of the apartment. When I unlocked the door, the place smelled like coconut body wash and the faint sweetness of whatever lotion Emily used.

She was in the living room, sprawled on the couch with a textbook open on her lap. The tank top she wore was so thin I could see the dark circles of her nipples. Her panties were pale pink, the fabric worn thin at the crotch, the elastic already starting to fray. She looked up and smiled like she’d been waiting.

“Hey, stranger. Jess texted me you might swing by. Want a beer?”

I took the beer. We talked about nothing—her clinicals, the asshole attending who’d chewed her out that morning, the new bar downtown. Every time she shifted, the tank top rode higher. Every time she laughed, her tits moved under the thin cotton. I sat at the other end of the couch and tried not to stare at the way the pink panties molded to the soft mound between her legs.

She noticed. Of course she noticed.

“You’re staring,” she said, voice light, teasing. “Jessica’s not the only one who likes attention, you know.”

I should have left. Instead I stayed. We ended up wrestling for the remote the way we always did—half play, half something else. She lunged across the cushions. I caught her wrists. She twisted, laughing, and suddenly she was straddling my lap, knees on either side of my hips, her pussy pressed right against the hard ridge of my cock through my jeans.

The room went quiet.

Emily’s eyes locked on mine. She didn’t move off. She rocked once, deliberately, grinding the damp heat of her panties along the length of me. “Oops,” she whispered, but there was nothing accidental about the second slow roll of her hips.

My hands settled on her waist. I could feel how little fabric separated us. The tank top had ridden up; the undersides of her tits brushed my chest. I could smell her—clean skin and the unmistakable scent of a pussy that was already getting wet.

“Emily—”

“Shut up,” she said, and kissed me.

It wasn’t soft. It was hungry. Her tongue slid into my mouth the same moment she ground down harder, rubbing herself against the zipper of my jeans. I grabbed her ass, fingers digging into the soft cheeks, pulling her tighter. The thin pink cotton was already soaked. I could feel the outline of her pussy lips spreading around the ridge of my cock.

We tumbled sideways onto the couch. She ended up under me, legs open, my hips between hers. I thrust against her once, hard, and she moaned into my mouth. The tank top was up around her neck now. Her tits were perfect—full, soft, nipples tight and dark pink. I sucked one into my mouth while I kept grinding, the friction of denim and thin panties driving us both crazy.

Her hands shoved at my belt. I helped her. Jeans and boxers shoved down just far enough for my cock to spring free, thick and already leaking. The head dragged across the wet crotch of her panties. She was so slick the fabric clung to her folds. I could feel the heat of her cunt radiating through the cotton.

“Fuck, Emily…”

She hooked her ankles behind my thighs and pulled. “Don’t stop. Just… keep rubbing. It feels so good.”

I lined up and thrust again. The head of my cock pushed against the soaked center of her panties. The fabric stretched. I thrust harder, grinding the full length of my shaft against her clit. She was panting now, hips rising to meet every stroke. The pink cotton was so thin and worn I could almost feel the actual lips of her pussy parting around me.

One more hard thrust.

The fabric gave.

There was a soft rip, almost inaudible under our breathing, and then the head of my cock sank straight into hot, dripping, impossibly tight pussy.

We both froze.

I was halfway inside my girlfriend’s sister. The torn edges of her panties framed the place where my thick shaft disappeared into her. Her walls fluttered around the intrusion, already clamping down. She was tighter than Jessica—younger, narrower, gripping me like a fist.

Emily’s eyes were wide. Her mouth opened on a silent gasp. For three long seconds neither of us moved.

Then she whispered, “Don’t you dare pull out.”

I pushed the rest of the way in.

My cock bottomed out in one smooth stroke, balls pressing against her ass, the torn pink cotton stretched obscenely around the base of my shaft. Emily’s back arched. A broken moan tore out of her throat. Her nails dug into my shoulders.

“Oh my god—you’re inside me. You’re actually fucking inside me.”

I stayed buried, letting her adjust, feeling every pulse of her cunt around me. Then I started to move. Slow at first—long, deep strokes that dragged my cock almost all the way out before sliding home again. Every thrust stretched the ripped panties wider. The wet sound of her pussy taking me filled the quiet apartment.

Emily wrapped her legs higher around my waist. “Harder. Please—fuck me harder. I’ve wanted this for so long.”

I gave her what she asked for.

I fucked my girlfriend’s sister like I’d been starving for her. The couch creaked under us. Her tits bounced with every impact. I sucked on her nipples while I pounded into her, tasting the salt of her skin. She was so wet that her juices soaked my balls and dripped down onto the cushions. The torn panties stayed stretched around my cock, a filthy reminder of how this started.

“Tell me how it feels,” I growled against her ear.

“So full—so fucking thick. Jessica never told me you were this big. God, you’re stretching me open.”

I flipped her onto her hands and knees. The tank top came all the way off. I shoved the ruined panties further to the side and slammed back into her from behind. The new angle let me go even deeper. Emily dropped to her elbows, ass high, face pressed into the couch cushion as she moaned with every thrust.

I grabbed a handful of her hair and pulled her head back. “You’re going to take every inch of this cock and you’re going to come all over it. Understand?”

“Yes—fuck yes—”

I reached under her and rubbed her clit in tight circles while I fucked her. Her pussy clenched hard. She came with a choked scream, walls spasming around my cock, juices flooding out around the shaft. I kept pounding through it, chasing my own release.

When she started to come down I pulled out just long enough to shove the torn panties the rest of the way off and flip her onto her back again. I pushed her knees to her chest and drove back in, folding her nearly in half. The new depth made her eyes roll. I could feel the head of my cock battering against her cervix with every stroke.

“I’m going to fill this tight little sister-pussy,” I told her. “I’m going to pump you so full of cum it’ll be leaking out of you for days.”

Emily’s answer was a broken, desperate “Please—come inside me. Breed me. I want to feel it.”

I lasted maybe twenty more strokes. The orgasm hit like a truck. My cock swelled and then pulsed hard, shooting thick ropes of cum straight into her cunt. I kept thrusting through it, forcing every drop as deep as it would go. Emily came again from the feeling of being filled, her pussy milking me greedily.

When I finally stopped moving we stayed locked together, both breathing hard. My cock was still half-hard inside her, the seal broken enough that a slow trickle of cum had already started to leak out around the base.

Emily looked up at me with glassy eyes and a wicked little smile. “We’re so fucked.”

I kissed her—slow, deep, tasting the shared secret on her tongue. “Yeah. We are.”