Lauren first became my step sister when her mum and her came to live with my dad and I, and we got on from the first time we met. My dads house was tiny so we shared my room, dad squeezed another bed in, but it was ok. We would go to bed at the same time and often lie in the dark chatting about stuff, she joined my school and it was like having a real sister. I began to get those sudden urges and I constantly had an itch between my legs to get rid of. Usually I wandered off to the loo and rubbed and poked until it went away. Lauren and I were still having our girl chats in bed, the topic now turning to boys and sex and as we chatted I often found my fingers feeling over my panties and pressing as we spoke, sometimes in the semi dark I could make out Laurens thighs up and making a tent under the sheet and I guess she was diddling too, sometimes I heard her gasping in the dark and the regular rustling sound of her rubbing, I would usually roll onto my tummy and quietly hump myself.
One day dad said he had a surprise for us after school, when we got home he said to look in our room and he had bought us bunk beds which were great as they gave us more space. Lauren took the top bunk and I was underneath. We were really close, I would often look at her when she changed, not in a Les way but watching her develop fascinated me and she had a cute tight butt.
One night after we had our chat I lay there in the dark and suddenly I felt like the bunk was moving, it was gently rocking and I realised Lauren must have been rubbing herself, every so often I heard her let out a little gasp and the rocking got faster then it would stop. She did this most nights and sometimes I joined in, both of us rubbing away in the dark. About a year ago I woke early on a Saturday morning and lay there. A while later I heard Lauren stirring above me, a few moments later the familiar rocking began so I guessed she was having an early morning rub, I peeked out from under her bunk and saw her foot jammed against the side of the bunk above me, I guess she had her legs apart and was rubbing away.
As I lay there I heard her faint gasp, the rocking would speed up then stop, a few moments later it would start all over again, I guess she was holding off. As I lay there my hand drifted down to my crotch, under my duvet I spread my thighs as wide as possible and traced the outline of my pussy through the material of my sleep shorts that had ridden up very tight against my crotch. As I thought of Lauren fingering away above me I squirmed down in my bed some more which pulled my shorts even tighter against my burning pussy, I felt my lips spread wide and bulging through the thin material and the seam had ridden into my slit and was pressing on my clit which felt delicious.
With one had I tugged my shorts and panties against my clit, the other I rubbed myself through the material which was now very wet. I often masturbated like this as it reminded me of how I did it when I was younger, I could feel the heat in my tummy and my thighs getting tight as Lauren gasped above me. Suddenly a great tightness hit my tummy and I buckled against my hands and shuddered to orgasm, above me I felt the bunk rock as I guess Lauren had cum as well. I lay there tingling all over and suddenly realised Lauren was getting down so I lay still and pretended to be asleep. The ladder was right beside my head, as I peeped out through slitty eyes I saw her thigh drape over and her foot find a step, for a moment this made her thighs stretched wide apart, one leg still on the bunk and one straight down, I looked right into the crotch of her pale blue panties which were stained dark blue and the outline of her puffy lips clearly visible.
I closed my eyes as she got down, I felt her looking at me and then I heard her pad over to the door, get her robe and then she went into the bathroom. I heard the shower go on so I sat up to get out myself when I looked over and saw her blue panties bundled on the floor with her nightie. The next thing they were in my hands and I was smelling her cum, then I stripped off and slid them on, they were slightly tight but felt good as the cum stained crotch sucked into mine, I lay on my bed on my front and humped my hands wearing them, shuddering to a quick orgasm as I thought of my pussy touching the same cloth that she had just poked around hers.