I was in this situation once, only I was the brother. My best friend and I were good friends for years, we only really had each other but we were cool with that, we only needed each other but we had such a good friendship nothing could get in the way, we could tell each other anything, but as time went on, my sister became more involved with us, exchanging time with her fellow girl friends for time with us. As soon as this had happened, along with her body language, I could tell something was going on, or at least something was going to happen! At first I found it hard to believe, I was also annoyed, would she steal him from me? But after much talking to my sister and my friend separately, I had come to understand and accept it. The relationship between them didn't last long, my best friend felt more comfortable single and spending time with me. It also turned out that something was going on two weeks before they officially told me, that secrecy made me sick, made me feel untrusted and I ignored the two for a few days, but becasue of my nature (which is to fix things that are broken (in a nut shell)) I had to go out and fix the friendship I had lost in a temper. ---------- I would say speak to your brother about it. If he is a nice, understanding person like myself, he will let both of your wants to go forwards and allow a relationship to form, however if you two get together and keep it a secret, the after results will be bad, trust me. Speak to him, most people will understand (I hope!) although I cannot guarantee success. Good Luck - Chris.