My sister and I have had a long history of masturbating and touching each other together. It started when she was about 8 and I was 10. We were both swimmers and one day while at a parent's friend's pool (alone our parents and their friend were inside) and I asked her if I could touch her "there." She said yes. Many times after that we did the same thing, each touching each other...it was natural brother/sister curiosity. Eventually our parents discovered what was going on and made us stop. They just assumed that it was normal for all brothers/sisters to go through.
When I was a little older, around 13-14 and discovered masturbation, I remember thinking what would it be like to masturbate with her. We'd play numerous games together and one day I asked her to play doctor. I gave her an exam and spent a particularly long time "examining" her vagina and breasts. I remember having huge boners during and amazing orgasms right after our doctor games. Finally she was the doctor, she was a little hesitant to see my penis but eventually I convinced her. She didn't masturbate it yet, but she did touch it, and explore it. I distinctly remember he commenting on the pubic hair that was developing. She was two years younger then me. When she was thirteen, I remember us having our first orgasm together. She was lying on her bed face down and I was rubbing her vagina from behind. I hadn't fingered a girl yet so I didn't really know what I was doing at this point. Eventually I did something right and I remember her asking me to "keep doing that because it felt good." I was lying on the bed next to her, dry humping the bed as I rubbed her. We both had an orgasm at the same time and it was amazing. I remember being embarrassed at how my boxers were soaked (she wouldn't let me be naked in bed with her). A few more glorious times we masturbated together. At one point each of us were totally naked. I finally convinced her to jack me off. Our best session at this age was in my room. She was naked on my bed, and I was naked in front of her. She was jacking me off and I was fingering her and touching her breasts. I cummed all over her and she was freaked out. We stopped for about a year after that.
When she was a freshman in high school and I was a junior we were home on a random day off that our parents didn't have. I accidently (really it was an accident) walked into her room, asking her if she was ready to leave. She was topless and in very sexy underwear. It had been over a year and a half since I'd seen her naked. Her breasts had really developed and I really wanted to see what her vagina looked like. I got a boner instantly. She covered herself up, but the thoughts of before must have been going through both of our minds. I asked her if she'd like "to do it" again. She said yes, but only if I "did it" to her, and I kept my clothes on. We never called what we did together masturbating or masturbation. It was just called "doing something." She kept the towel over her breasts and slowly removed her underwear. Her vagina had really developed. She had a batch of pubic hair and had a gorgeous vagina in general. She lay on her bed with her legs open. I fingered her and even went inside but she asked me not to do that. She did ask if there was anything "aside from going in" that would make it feel better. I told her that I could lick her vagina if she wanted and put both of my hands on her breasts. She agreed to let me lick it for a minute. Licking her vagina was one of the best moments we ever had together. I got some pubic hair in my mouth and some fluid which tasted great. I licked her for much longer then a minute. She loved it and I remember her panting while I did it. I was dry humping her bed while doing this. We orgasmed with my tongue in her vagina.
I never gave her head again but a few more times we've masturbated together. She's going to be senior in high school and I'm in college, and we still masturbate, very rarely though, together. Our last session was a few weeks ago, and she actually asked me. She had a headache and was lying on the couch. She said "can you do something so I can relax?" To this day we've never said "masturbate" in front of each other. I fingered her through her panties (she wouldn't let me go under) and my fingers got soaked. After she was done I jacked off in my room licking and smelling my fingers.
I've enjoyed this bond we've developed over our lives. Neither one of us thinks its gross, and I enjoy giving her orgasms. I routinely masturbate to these memories, and was so happy to tell the whole story on this site! Let me know what you think.