I don't know what the Original Poster is thinking of doing in this situation, but I would say to myself : "I'm at Uni, making something of my life. I remember when I was my brothers age. I wasn't fully grown up and I didn't know I was annoying people so much. It's his problem if he wants to ruin a relationship, not mine. The best thing for me to do is act calm when around him and not get wound up by him. At the end of the day, I have my life to live, and he has his life to live. If the two clash, then thats unfortunate, but its not necessarily a problem.