If you're out to your friend (the one you know him through), how about bringing it up with him? Maybe you can at least find out a few things you have in common with this guy and use your friend's help to befriend Mr. Straight. Start by becoming his friend and get to know him without confessing that you like him or telling him that you think he might be gay. Genuinely earn his trust. If he is into guys and he ends up being into you, it will happen naturally. Or, as you get to know him, you may realize you don't like him as much as you thought. Or, you could realize you like him even more and he could turn out to actually be straight and your heart gets broken. You're choosing the challenging path here, just keep that in mind. It's going to take a lot of patience and has only a small chance of working out the way you want it to. If you're willing to accept the low odds and the risk of possibly being disappointed, then go for it.
