I lifted my arms to free myself and ground back into his pelvis where I could feel his cock growing inside his pants. He pushed back while grabbing my...small but firm breasts, inciting a sigh from me. I tried to turn around to face him, but he stopped me. “Not yet” and he unclipped my bra and dropped it to the floor. He began to tease me, brushing his fingers along my flat stomach up to the bottom of my tits. I could feel myself getting wet from just this alone, and my small nipples were rock. When I thought I had her secured well enough I glanced at theclock and said 'done', then sat back in my chair to watch her try to get free. There is nothing at all incestuous about our relationship, but I have toadmit sitting there watching as my sister squirmed in her bonds, moaning throughher gag and breathing hard that I was getting excited. As I said, my sisteris gorgeous- always has been- and seeing her there like that, well, she lookedhot. I tried to ignore that she was my sister, but. I fucked my stepsister hard and she soon reached climax again and orgasmed. After she finished cumming I pulled out of her and moved her to sit on the edge of the couch. I moved and kneeled between her spread legs and re-entered my cock into her soaking wet cunt. I grabbed onto her thighs and started fucking hard in and out of her cunt making her scream from the pleasure. I then reached the vurge of cumming and pulled my cock out of her puss and pressed it against her clit as it exploded. He was naked and I looked down and saw his arm moving up and down. I was behind him so he did not see me walk in. 'What do you think you are doing' I shouted out. Mark jumped out of his skin, he didn't know what to do he tried to cover his privates and hide my knickers behind his back. I called im all the dirty fuckers under the sun and threated to to Mum and Dad on him when they got back from work. He begged me not too. I looked down at his pathetic skinny body and thought I could have some.