Nothing at first

As I looked out into the hall I took one last look at my sisters door. It was still open but just as was about to turn away, I saw her bare arm reach out and close her door. I looked for a few more moments before finally shutting the door.

I hadn't seen much of her but it was enough to set my mind racing.

I imagined her slipping out from under her blankets revealing her naked body. Her inner thighs are still damp from her self exploration and from the excitement of seeing her brother naked just a few minutes ago. Her hips swayed sexily as she walked and her perky breasts bounced as well, her nipples as hard as rock.

I imagined that she paused at her door, struggling to decide whether to follow me or not. Eventually she decides against it and shuts the door.

She returned to her bed after retrieving her phone. She didn't bother with the covers this time and lay bare to the room as she slipped her fingers between her legs and resumed pleasuring herself. Only this time she had more recent images filling her mind now.

I was awoken from my fantasy by a noise. I was standing in the shower, water running down my body, hand on my swollen cock. I stopped jerking myself off and looked around the room.