youre just afraid of rejection. however, he might tell his brother and it might feel funny, but the truth of the matter is, what have you got to lose? so what if you get rejected, but if you don't, you'll be that much more ahead.
and starting up a converstation? it will depend on the situation, but simply by saying hi occasional, he won't think any differently of you. he already knows your brother so that actually might help the situation. start by talking to your brother about it and see what he has to say. raverboy
...this is just my perspective on the situation...