I didn't even get the chance to answer.
Mia's eyes flashed with that victorious, bratty gleam. The next second she swung one smooth thigh over my mattress like she owned the damn thing. The ladder creaked—loud enough that my stomach dropped—but she didn't give a fuck. She was already straddling me reverse-cowgirl, gripping the metal rails for leverage, ass facing me.
Her black thong was yanked to the side. Her soaked pussy lips glistened in the moonlight, hovering right over my throbbing cock.
"Shhh," she whispered, even though I hadn't made a sound. "Not a fucking noise, little bro. Renovation crew is sleeping right downstairs. You wake them and we're both dead."
She reached back—fingers still slick from her own cunt—wrapped them around my shaft, and lined me up. The fat head kissed her entrance… then sank inside with one greedy roll of her hips.
I bit my own forearm to choke back the groan. She was impossibly tight, velvet walls clamping down like a fist. Inch after inch disappeared until her perfect ass settled flush against my abs, every thick inch of me buried to the hilt inside my stepsister.
"Mmmph…" she breathed through clenched teeth, head dropping forward, hair curtaining her face. Her knuckles turned white on the ladder.
Then she started riding.
Slow at first. Controlled. Filthy little circles that made the bunk frame squeak dangerously. Every downward stroke dragged her slick walls along my entire length. Every upward slide left my cock shining with her cream.
The wet sounds were obscene—soft, sticky schlick-schlick-schlick that filled the dark room. Her ass cheeks jiggled with every bottom-out. I could see everything: the way her pussy stretched obscenely around me, the shiny trail of her juices running down my balls, her tight little asshole winking every time she ground down hard.
"Fuck… you're so much bigger than I imagined," she panted, voice barely above a whisper. "All those nights I listened to you jerking off through the wall… I knew you'd feel this good stretching me."
I grabbed her hips, fingers digging in, trying to slow her before the whole bed gave us away. But Mia just smirked over her shoulder and slammed down harder—balls-deep in one punishing stroke.
The bunk creaked loud.
We both froze.
Hearts hammering. Listening.
Downstairs… nothing. Just the distant hum of the dehumidifiers.
She bit her lip until it went white, then bounced faster—needier—chasing it. Her tank top rode up; I watched her spine arch every time she took me to the root.
"I'm close," she hissed. "Don't you dare pull out. I want it inside. All of it."
My balls tightened. The pressure was insane. I could feel her pussy fluttering, milking, begging.
"Mia—" I choked out.
"Fill me, Alex," she demanded in that bratty whisper. "Breed your stepsister's tight little cunt. Right. Fucking. Now."
That was it.
I slammed up into her once, twice—and exploded. Thick ropes of cum pumped deep inside her, pulse after pulse, so much that on the third spurt it started overflowing around my shaft. Mia's thighs shook. She came with me—silent except for the tiniest choked whimper—her pussy clamping down like a vice, milking every last drop from my balls.
We stayed locked like that for a long moment: me buried to the hilt, her ass pressed tight, warm cum already leaking out around my softening cock and dripping down her thighs in sticky trails.
Finally she slid off with a wet pop. A fat glob of my load spilled onto the sheets between her legs. She looked down at it, then back at me with the filthiest little grin.
"Guess we're sleeping in the wet spot tonight," she whispered, climbing back down the ladder like nothing had happened.
She flopped onto the bottom bunk, pulled the sheet over herself, and let out a satisfied little sigh.
"Night, little bro."
I lay there on the top bunk, cock still twitching, covered in her cream and my own cum, staring at the ceiling.
Four months.
We'd already crossed the line on night one.
I didn't know how the hell we were supposed to keep this quiet.
I didn't know if I even wanted to.
End Ch 03.