He smelled my sister's butt [her photos]

In 2013 my sister invited me to sleep with her on a mattress next to her bed. I had already seen her in underwear before but at that moment with 18 years old and hormones raging, seeing her massive ass got me hot. That's why I asked to stay over often, to see her ass. One night I was sleeping uncovered and I approached to smell her butt and she used the word 'pussy' while I was masturbating; a rich smell! Writing this is making me hard.

From that moment on, every time I stayed over, I would wait for her to fall asleep and masturbate next to her smelling her used panties. I no longer cared it was my sister, all I wanted was to break her cherry and leave it dripping with cum.

This lasted 2 years, I don't have that thought anymore although sometimes I look at her butt.