I'll finally do it with my brother, I think

I (f22) have been trying to get my brother (19) to catch me doing something for months. I leave the door slightly ajar when I shower and when I change in my room because it's right next to his. Yesterday he stopped and just stared at me while I was changing. He probably only saw my ass. I didn't notice until I turned around and he was there and then he ran to his room. I think this is the start of, hopefully, something more.