When I agreed to spend the weekend at Mark’s family lake house, I was mostly picturing late-night beers, some terrible fishing, and joking around by the old firepit. But what I didn’t realize was that his younger sister Emily would be joining us. I’d met her a few times before, mostly in passing, but never really talked much. She’d always been Mark’s smart, sweet little sister, a sophomore at college, barely on my radar. But the moment she walked in that Friday night, dropping her bag by the door, it was obvious how much she’d changed since last summer.
Emily had this easy confidence—messy blonde hair, faded jeans, and a tight white tank top. She flashed me a grin. “Hey, Alex, long time no see!”
“Yeah, Emily, good to see you,” I replied, trying to play it cool. I caught myself staring a beat too long as she reached up to tuck her hair behind her ear—there was a tiny gold stud in her nose, which I definitely hadn’t noticed before.
The first evening was pretty tame. Emily and Mark retreated to the kitchen together, catching up with their parents on FaceTime. I wandered to the back porch, listening to the late-summer crickets, but my mind kept drifting: when did Emily get so… grown up? The whole night, I caught myself glancing her way, watching the line of her neck as she laughed at her brother’s dumb jokes, the way her t-shirt clung to her body. It felt weird, wrong even, but I couldn’t shake the heat creeping up my neck.
The guest rooms were down the hall from each other. Mark was out cold by midnight, but I tossed in bed half the night, picturing Emily’s smile, the curve of her waist. Part of me tried to shove it away: this was Mark’s little sister. This was stupid. But it didn’t help.
The next morning, the three of us took the paddles out. It was sunny and warm, the kind of late August day that wraps around you. Emily wore a black bikini under an open shirt. She joked with Mark, splashing him, but I noticed her glancing over her shoulder at me. I wondered if she caught me staring, or if Mark noticed the crackle of weird electricity when our eyes met.
By midday, Mark was already yawning. “Dude, I didn’t sleep at all last night. Wake me if you do anything fun.” And just like that, he wandered off inside, leaving Emily and me alone by the edge of the dock.
I debated internally for a few seconds: stay or go? But she shot me a sly look, one eyebrow arched. “You seem quiet, Alex. Everything okay?”
“Yeah,” I shrugged, “just tired, I guess.” Which was bullshit; I was buzzing.
She squinted out over the water. “You don’t have to act weird around me. I’m not a kid.”
There was a challenge in her voice. Something in my chest twisted. “I know you’re not,” I said, voice rougher than I meant.
We sat in silence for a minute, the air thick between us. Then she said, “Want to go for a swim?” She kicked off her shorts, shucking her shirt and leaving only that black bikini. It was so much skin—smooth, tanned, and almost sinfully off-limits. She dove in, surfacing with a flip of her hair.
I hesitated—should I follow? Everything in me screamed that Mark would kill me if he knew what I was thinking. But when Emily swam toward the dock, her hands gripping the ladder beside me, all rational thoughts seemed pointless.
“Are you coming in, or what?” she asked, grinning.
I tore off my shirt and jumped in. The water was cold and shocking, but having her so close was electric.
We splashed around, racing, laughing. Finally, breathless, we rested at the edge of the dock. Emily was so close I could see little freckles across her nose.
She looked up at me. “You don’t have a girlfriend anymore, do you?”
“No,” I said softly. My chest felt tight.
“So why are you acting so nervous?” Her voice was teasing, but her eyes were steady, watching me.
I swallowed. “It’s… you know, Mark.”
She drifted closer. “Mark’s not here.” The sentence felt like an invitation and a dare at the same time.
Before I realized it, she leaned in and pressed her lips to mine. The kiss was soft, careful at first. She tasted like lake water and sunscreen. I froze for a half-second, and she pulled back, her cheeks flushed. “Sorry, I—”
I didn’t give her time to finish. I kissed her back, deeper this time, my hands gripping the dock to keep from shaking.
When we finally broke away for air, she tilted her head. “See?” she whispered, her smile devilish.
We swam back to shore in silence. I followed her up the path, my eyes glued to her hips swaying in front of me. Upstairs, I hesitated again outside her bedroom door. Was I really about to do this? Guilt twisted in my gut—Mark was just down the hall. But Emily opened the door and looked over her shoulder.
“Are you coming?”
I stepped inside. My heart was pounding, but I couldn’t stop myself.
Emily closed the door and sank onto the bed. She looked nervous for the first time, fingers knotting in the blanket. “Is this… weird, Alex?”
I shook my head—too fast, probably. “It is, but I want you. I can’t stop thinking about you.”
My hands trembled as I reached for her, brushing a strand of hair from her cheek. She looked up at me, eyes wide, lips parted. I kissed her again, slower this time, tasting her, letting myself get lost. Her hands slid up my back, tugging at my trunks.
“Lock the door,” she whispered.
I did. My breath was ragged. We fell onto the bed together, tangled up. She giggled when I fumbled with her bikini top, then moaned quietly as I traced her breasts with my tongue. Her skin tasted salt-sweet, sun-warm, so perfect I lost myself.
Her hands were everywhere—scraping lightly down my chest, pulling me close, sliding into my hair. “You feel so good,” she gasped, arching into me.
I tugged her bikini bottoms down slowly, my lips tracing a line down her stomach. She made a quiet, pleading noise—something I’d never imagined hearing from her.
“You want this?” I asked, needing to be sure.
She nodded, grabbing my hand, guiding me between her legs. She was soaking, hot and slick. I touched her, teasing, feeling her thighs tense around my fingers.
“Oh fuck, Alex,” she breathed, her voice trembling. I grinned, emboldened, sliding two fingers inside her, feeling her hips buck, her nails digging into my shoulder.
When I couldn’t take it anymore, I fumbled off my trunks. She tugged me on top of her, wrapping her legs around me. That moment—bodies tangled, hearts racing—felt almost surreal.
She pulled me to her, our bodies meeting, heat and urgency stealing the last of my hesitation. I pushed inside her, both of us gasping at the contact. She was tight, perfect, moving with me, eyes locked onto mine.
We kept moving together, riding a wave of desperate need. She moaned my name, quiet but urgent, hands in my hair, biting my shoulder when she came, her whole body shaking. I followed soon after, shuddering, barely biting back a cry as I came inside her.
After, we lay side by side, catching our breath. Her head rested on my chest, her hair damp and wild. We didn’t say anything for a long time.
I stared at the ceiling, mind racing—the guilt, the excitement, the memory of her body under mine. This was crazy, reckless, possibly the worst idea I’d ever had. But when she turned over, smiled, and traced circles on my chest, I knew I’d do it all over again.
And that weekend at the lake house became the one secret Mark never found out.