WINCEST, stories about your experiences, no matter how close you got, ill start

I was 17 at the time, 2 years ago, and my younger sister was 14 (similar looking to pic, minus the braces). She was in track at the time and had that perfect firm ass with nice thin legs. On weekends maybe once or twice a month we would stay up late watching a movie and she would rub my back if I in turn would rub her legs. We did this many times with nothing sexual involved. However this night I was feeling rather horny and adventurous, and due to this cesspool known as 4chan, I started getting thoughts... As the movie went on and I was rubbing her legs I slowly started making my way up her thighs until i was at the cusp of her ass, and to my surprise, no rejections from her not even the slightest of flinches. To be continued...