When I was 15 I was totally sexually infatuated with my 13 year old little sister, Laura. Wanking off meant thinking about her, but up till then I'd only really considered it an exciting fantasy, never imagining I'd ever do anything real.
The day this changed we were both off school during the long summer break and our parents were at work. It was late in the morning and I was lying in bed, naked from the waist down, slowly stroking my cock and just starting a fantasy about my hot little sister. The noise of my sister's room door opening intruded briefly, then half a second later my eyes shot open as I realized my room door might not be properly shut!
I quickly covered myself and then lay still, hearing sis walk down the hall and then return a few minutes later, shutting her door. Had she seen me? I had to know.
I jumped out of bed, slipped some underwear on and quietly approached the door. My room was an 'L' shape, with the bed near the top and the door at the other end. The door was opened only an inch or two, but there was a gap near the hinge where sis could have seen. From that angle she would have been able to see more than two thirds of my body, with the wall cutting off my shoulders and head.
I opened the door and slipped out into the hall and returned the door to its previous position. With the hall light on and the curtains in my room closed it was immediately obvious that sis couldn't have seen anything. Even when I turned the hall light out it was still difficult see anything without pressing your face right up to the hinge.
I should have been relieved, but was surprised by how disappointed I felt. As an experiment, I switched on my room light and went back out. With the hall light on it was the same story, but turned off and suddenly a brilliant thin column of light revealed my room's interior. It wasn't wide enough to immediately draw attention, but sis *might* have seen me under such conditions and moved closer for a better look.
My heart was beating fast and my dick was fully erect at the idea. On a whim I dropped my underwear and stood there in the hall, half naked. If sis came out of her room now she'd see everything. My dick throbbed in pleasure at the notion. But explaining why I was standing there naked with a hard on would certainly be awkward.
Okay, I'd let her catch me wanking...or at least give her the opportunity.
I walked into the bathroom and grabbed a hand towel. Returning to the hall, I reached up with the towel wrapped around my hand and removed the bulb from the light-socket. I banged it on the floor two or three times and then returned it and flicked the switch, smiling when the hall stayed bathed in darkness.
Feeling a mixture of nerves and horniness I reentered my room and closed the door to its original position. My room light was on a dimmer switch and I turned it half way up, not wanting to be too obvious and then lay on my bed with my hand on my dick waiting for my sister.
Five minutes passed, then ten...surely she wasn't going to stay in her room all day! I lay there still, totally focused on my task, not daring to masturbate in case I got over excited and caused Laura to miss the show.
After twenty minutes of lying there I impatiently got up and put my ear against the door to see if I could hear sis moving about. I couldn't ever remember being this horny. I was even shaking/shivering slightly.
Fuck it, I thought, and opened the door another inch, stared at it for a second then added another three! The gap near the hinges was now two or three times the original width. On my way back to the bed I flicked the dimmer to full brightness and removed my t-shirt, lying back down fully naked...fully committed.
Five minutes later I heard my sister's door open. She was the most beautiful girl I knew, but you'd never call her light footed. Thud, thud, thud, thud...silence!
I slowly started jerking my cock. Every second I didn't hear her footsteps I was more sure she was watching, seeing her first hard dick. I closed my eyes and started to fantasize about her: imagining striping her naked, kissing her gorgeous flesh and finally sinking my cock deep within her tight, perfect pussy.
The pleasure was enormous. Why on earth hadn't I done this before? I knew I would't be able to last long and stroked as slowly as I could. Soon I'd be cumming, exposing that most intimate moment to my little sister. And why not? It was her I always thought about. Surely it was her right.
In my fantasy I was making love with my sis on the bed. As I imagined filling her with my cum, I shot wave after wave over my chest and stomach, determined to give her the best show I was capable of.
Finally spent I just lay there. A few seconds later I heard my sister's room door quietly shut. Sanity returned, I worried how she'd react. One thing was for certain: things would never be the same.