My name is Ethan. I'm twenty, home from sophomore year at Northwestern, and I've spent the last six months convincing myself that the way I look at my sister is normal. Riley is twenty-two, a senior at UW-Madison, and every time she comes home she's a little more… everything. Taller in confidence, sharper in wit, and—God help me—curvier in all the places I pretend not to notice.
This trip was Dad's idea: a long weekend at Uncle Ray's lake house in Door County, Wisconsin. Eight hours in the Suburban, just the four of us. Mom packed enough snacks to feed a marching band. Dad queued up his "road-trip classics" playlist. Riley and I got exiled to the third row because the middle was stuffed with coolers and a folded kayak. The luggage formed a chest-high wall between us and the front seats; the rearview mirror showed nothing but a duffel printed with cartoon pineapples.
We left at dawn. The first hour was easy: Riley asleep against the window, her hoodie riding up to reveal a strip of tanned stomach and the silver ring in her navel. I stared at the cornfields and tried to think about anything else.
By hour three, the AC was losing the battle against July. Riley peeled off the hoodie, leaving her in a thin white tank and denim cutoffs. The tank clung to the swell of her breasts; the cutoffs barely covered the curve where thigh met ass. She stretched, arms overhead, and the fabric lifted another inch.
"Trade me spots?" she whispered. "I'm dying over here."
I slid over. Our thighs touched—bare skin on bare skin. Static shot up my leg. She didn't move away.
Hour four: Dad pulled into a Kwik Trip for gas and coffee. Mom went inside for the bathroom. Riley and I stayed in the car, windows cracked, engine off. The sudden quiet felt huge.
She turned to me, knees pulled to her chest. "Remember when we were kids and built blanket forts in the back of Dad's old van?"
"Yeah. You always hogged the flashlight."
She laughed, soft. "We'd tell ghost stories until Mom yelled at us to sleep." A pause. "Feels like that now. Hidden."
My pulse kicked. "We're not kids."
"No," she said, eyes flicking to my mouth. "We're definitely not."
The moment stretched, thick as honey. Then Mom's door opened and the spell cracked. Riley faced forward again, but her pinky brushed mine on the seat between us. We left it there.
Hour five: traffic slowed to a crawl outside Milwaukee. Brake lights bled red across the windshield. Dad cursed under his breath. Mom dozed. Riley pulled the big striped beach towel over our laps "for the sun." The luggage wall swallowed the motion.
Under the towel, her hand found my knee. A question. I didn't stop her.
"Ethan," she breathed—so low I felt it more than heard it. "Tell me if you want me to stop."
I couldn't speak. I turned my hand palm-up. She laced our fingers. Then, slowly, she guided my hand beneath the frayed hem of her shorts.
No panties. Just warm, slick skin. My fingers trembled against her. She was already wet, swollen, pulsing. I traced one careful circle around her clit and she bit her lip so hard I thought it might bleed.
"Riley—"
"Shh." She shifted, spreading just enough for two fingers to slip inside. She was scalding, tight, clenching like she'd been waiting years. Maybe she had.
Dad's blinker clicked—he was merging left. The car swayed. Riley used the motion to rock against my hand, tiny, silent thrusts. The towel rose and fell like a heartbeat.
I found a rhythm: slow curl, press, retreat. Her breath hitched against my neck. She reached for my shorts, fumbling the button. I lifted my hips a fraction; she freed me. My cock sprang into her fist, aching, leaking.
We froze when Mom stirred. "You kids okay back there?"
"Fine," Riley called, voice steady as glass. Under the towel, her thumb swiped over my tip, spreading pre-cum. Mom settled again.
Riley's eyes met mine—dark, wide, terrified and electric. "First time touching you like this," she whispered. "Wanted to since prom night. You wore that stupid blue tie."
I remembered. She'd danced with her date while I watched from the bleachers, jealous in ways I couldn't name.
I pressed deeper inside her; she clenched hard. Her stroke matched my pace—wet sounds muffled by the towel and the hum of tires. Traffic crawled; every brake light felt like a spotlight.
Dad's phone rang—Bluetooth. Uncle Ray checking ETA. Riley's hand never stopped. I added a third finger; she whimpered into my shoulder, teeth grazing skin.
"Almost there," Dad said. "Forty minutes."
Forty minutes. I was going to come in my sister's hand with our parents twenty-four inches away.
Riley sensed it. She squeezed the base of my cock—hard—stopping me. "Not yet," she mouthed. Then, reckless: "I want to taste you."
My brain short-circuited. She bent forward, pretending to dig in her bag. The towel shifted. Her mouth closed over the head of my cock—hot, wet, impossible. One slow suck, tongue swirling, then she sat up, lips shiny, eyes daring me to lose control.
I couldn't breathe. My fingers moved on instinct, thumb on her clit, two inside, curling. She buried her face in my neck to muffle the gasp as she came—hard, sudden, a rush of wetness soaking my hand and the seat beneath us. The clench dragged me over: I bit the inside of my cheek as I spilled into the towel, pulse after pulse, her fist milking every drop.
We stayed locked like that—her trembling, me shaking—until the car turned onto gravel. The lake house loomed ahead, windows glowing gold in the dusk.
Riley tucked me away, smoothed the towel. Our hands were sticky, hearts hammering. She met my eyes.
"Tonight," she said, voice raw. "After they're asleep. Your room or mine."
I nodded, throat dry. The luggage wall had kept our secret. For now.