When my dad remarried a few years ago, I not only gained a step-mother but also a step-sister. It was very weird having a girl in the house that was the same age as me. Before my father's new union my only sibling was my brother and he lived with my mother, so I was not used to sharing the attention. Worse yet was that Lisa was one day older than me so I was not even the oldest anymore. Just when it was beginning to look like having a live-in sibling was going suck, I learned that having a sister could be a great thing.
She and I were both eighteen year old seniors as we both started kindergarten late. All of Lisa's friends were eighteen and some were even a little older. During our senior year she and I became pretty close and I would regularly express my interest in a certain one of Lisa's friends and low and behold that very girl would spend the night at our house and she and I would hook up with in the space of a couple of weeks of my mentioning my interest to Lisa. Now I was of course suspicious as to why my step-sister would let me sleep with her friends, but hey I wasn't going to question it.
When our parents first got married Lisa was short and chunky, but in the space of three years she has lost the baby fat and grown a few inches in height. Lisa has grown into a nice looking young lady. Her long blonde hair and green eyes, along with an incredible ass and long athletic legs made her by far the prettiest girl in our school. Shortly after she and her mom moved in with my dad and I, Lisa made two new friends, one was my cousin Becky and the other was her boyfriend Andy. Andy was a year older than us and a complete geek and by the time Lisa hit 18 she was way too good looking to be with the likes of him, but they had been together so long that she did not care. She said she loved him and she would not leave him. Well shortly after our graduation, Andy dumped Lisa for a band nerd and Lisa was devastated.
That dickhead dumped her right after the graduation ceremony and being a good brother I skipped the post ceremony parties and stayed at home with Lisa. I bought some alcohol to help her dull her sorrows and mine since I was missing the after graduation parties. She cried for hours and drank a ton of alcohol. It wasn't long before she was totally wasted and started asking what she had done that was so terrible and was she that disgusting and ugly and all the other things that teenage girls ask themselves and others after a breakup. I sat with her on the couch in the sitting room in the basement of our house and tried to comfort her as best I could. I could not believe that I had given up a night of parties and drunken sex and I started to seriously regret my decision to stay home with my sobbing sister. At some point I must have given away what I was thinking because Lisa looked at me and told me how nice I was for staying with her and then she gave me the answer to the question that had been bugging me for most of the school year.
"You don't have to do this to pay me back you know" Lisa said to me. I turned and looked at her for a minute and finally asked her what she meant. "I'm sure by now you noticed that all the girls you liked always seemed to spend the night here, well that was my idea." I was not really sure what to say to her and all that came out was a lame "thanks!" Lisa smiled slightly and told me that she had selfish reasons for setting me up with her friends. I watched as her face turned red and she looked at the floor and my head reeled as she began to explain. "I used to watch you do it. I liked you but I thought you wouldn't do it with me since I was your sister and I thought that watching you was about as close as I was going to get. So I started inviting girls over that I knew you liked so I could watch you do it and masturbate. I kept on doing it because I would always have the best orgasms while watching you with my friends."
