Is it normal that I fear my brother might be attracted to me?

I think you should drop plans of living together and throw cold water all over this relationship because nothing good will come of it.

You have enough to deal with as a young gay male. You do not need the problems of a thuggish, manipulative, half-brother who obviously wants to experiment with incestuous sex.

If you are going to screw anything, screw your head back on right.