Oh god what was I thinking, how could I allow that! After all, he's my s***r, we can't do something like that, it's forbidden! But somehow I was so drawn to him and just couldn't do anything about it. I have often imagined what it is like to feel his long cock in my small tight pussy and then the day finally came when we were alone and it really happened but we can do it at all, after all I am his s***r !? But maybe that was exactly what was so exciting about the whole thing!