Tension Between Flatmates

It may seem really small, but it is something that has been on my mind for quite some time. I share a flat with two other girls, both super good friends of mine. With one of them I've shared quite a lot of flirty comments, looks, touches,... there has always been some sexual tension between us. I would say, that she is the dominant part in our relationship but she is also very caring and respectful.

Sometimes when I sit on our couch she will slide behind me, one leg on each side of me, pull me close to her and hug me. I imagine that she will go with her natural liking for control, hold me, kiss and bite my neck and start fingering me from behind. The act of not really knowing what is happening, being slightly dominated and the complete comfort und trust that comes from the body position, is something I enjoy a lot.