I think very few people are sitting around with lots of manifested aggression that are too caught up in playing a perceived character, and thus self-isolate themselves. Some people DO want to be left alone though. I've had my fair share of people trying to talk to me when I seem to be the person left out, before I try to explain in a nice way that I was not left out, but willfully reclusive. :)
I guess I'm now the kind of person that can walk up to just about anyone in class and try to find what kind of things they like/dislike, or if they have any good ideas on the course/future plans etc. I don't always do this, of course, but sometimes it comes in handy.