I have two cases, kind of similiar to this, actually.
My Freshmen year in Highschool I met two boys that I honeslty could not STAND. In my Writing and Dec class, one of them who at the time I always said looked like Drew Carey, used to try and pick on me. We'd get in "tiffs", but nothing more. We never got along really, and I didn't care much for the guy. Then, later that year we both got involved in a school activity, and to this day we're awesome friends. We both have the same interests, and do tons of stuff together. How was I supposed to know he was so cool?
Also, in the same year I knew another boy who I always thought was a jerk. We started hanging out, and boom, we're both good friends now. All three of us hang out and do stuff together. It just goes to show, that you really never know who a person is, untill you have the chance to really "meet" them.