Sinful Geometry (A collection)

Chapter 1

I moved into the building on a Tuesday.

Third floor, unit 3B. The place was small but clean, with decent light and walls that looked solid enough. I didn’t think much about the neighbor in 3A until the first night.

It started around midnight.

I was lying in bed with my laptop open, half-working, half-scrolling, when I heard it. A low, rough sound—definitely a man. Then a woman’s sharp inhale. The headboard knocked once against the shared wall. Then again. Steady. Deliberate.

I froze.

The walls weren’t thin enough for full sentences, but they were thin enough for the rhythm. Skin on skin. A muffled curse. Her voice climbing higher, breaking on every thrust. His voice deeper, controlled, like he was telling her exactly what to do and she was taking it.

I should have put on headphones. I didn’t.

I sat there in the dark, laptop forgotten, thighs pressed together while the sounds went on and on. When she finally came, it was loud enough that I felt it in my chest. He didn’t stop right away. He kept going until she made a broken, helpless noise, and only then did everything go quiet.

I lay awake for another hour, pulse thudding between my legs, pretending I wasn’t soaked.

The next night it happened again. And the night after that.

By the fourth night I knew his schedule better than my own. He’d come home late. There would be the low murmur of voices, sometimes a soft laugh, then the unmistakable shift into something heavier. Sometimes it was fast and rough. Sometimes it stretched out, slow and filthy, until I was biting my own pillow just to keep quiet.

I never saw him clearly. Just glimpses in the hallway: tall, dark hair, broad shoulders under a black shirt, the kind of quiet confidence that made people step aside without thinking. Once our eyes met for half a second when we both reached for the mail at the same time. He nodded once. I looked away first.

I told myself it was none of my business. That listening made me pathetic. That I needed to get laid so I could stop obsessing over a stranger fucking someone else through the wall.

Then Friday night arrived.

I came home exhausted, dropped my bag by the door, and went straight to the shower. The water was still running when I heard the front door of 3A open and close. Voices. His low and calm. Hers lighter, already a little breathless.

I turned the water off and stood dripping in the steam, listening.

They didn’t waste time.

The first solid thump against the wall made me jump. Then another. Faster. I could hear the wet sound of skin now, clearer than before. Her voice rose in short, punched-out moans. His stayed quieter, almost conversational, except for the occasional rough “take it” or “that’s it.”

I didn’t go to the bedroom.

I walked naked to the living room wall that separated us and pressed my palm flat against the cool plaster. The vibrations traveled up my arm. Every hard thrust landed against my hand. I closed my eyes and let my other hand slide between my legs.

I was already wet. Shamefully so.

I worked two fingers inside myself in time with the rhythm on the other side of the wall, biting my lip hard enough to taste copper. When she started begging—actual words this time, broken and desperate—I came so hard my knees nearly gave out. I had to brace myself against the wall, forehead pressed to the paint, breathing through my mouth while the orgasm rolled through me in waves.

On the other side, he finished with a low, guttural sound that made my empty cunt clench around nothing.

Silence followed. Then soft movement. The sound of a shower starting in his apartment.

I stayed where I was, fingers still inside myself, heartbeat loud in my ears.

That was the night I stopped pretending this was just curiosity.

I cleaned up, pulled on an oversized T-shirt, and sat on the edge of my bed staring at the shared wall like it might answer me. I didn’t know her name. I didn’t know his. All I knew was the sound of him taking her apart and the way my body reacted like it was personal.

Around one in the morning I heard his door open again. Soft footsteps in the hallway. Then nothing.

I should have stayed in bed.

Instead I walked to my own door, unlocked it, and cracked it open just enough to look.

He was standing in front of 3A in dark sweatpants and nothing else, phone in one hand, the other running through damp hair. The hallway light caught the lines of his shoulders and the trail of hair disappearing under the waistband. He looked tired. Satisfied. Completely unaware he was being watched.

Then he turned his head.

Our eyes locked.

For three full seconds neither of us moved. My pulse slammed against my throat. His gaze dropped once—over the bare length of my legs under the T-shirt—then came back to my face. Something unreadable passed through his expression.

I closed the door.

I stood there with my back against it, heart racing, the taste of adrenaline sharp on my tongue. On the other side of the wood I heard nothing for a long moment. Then the soft click of his own door shutting.

I didn’t sleep.

I lay in the dark replaying the way he’d looked at me, the way the air had gone tight between us in that narrow hallway. Every time I closed my eyes I heard the earlier sounds all over again—her moans, his controlled voice, the headboard hitting the wall in a steady, ruthless rhythm.

Only this time, in my head, the woman making those sounds was me.

I pressed my thighs together and felt how wet I still was. My fingers slid back between my legs without permission. I came again, quieter this time, biting the pillow, imagining his weight, his voice, the exact pitch of the sounds he made when he finished.

When it was over I stared at the ceiling and whispered the only honest thing left in my head.

“Fuck.”

I was in so much trouble.

And I already knew I wasn’t going to stop.