Speaking from a personal experience, I've always been the outsider, or at least that's how I felt.
Starting from kindergarten until the apotheosis reached in high school, there's been a feeling of exclusion from the inner circle: there was this group of the "cool" people, who just walked together everywhere, sat together at lunch and so on. Maybe they didn't even do anything special, but everyone would have killed to be a part of that group, with those specific people who are just too distant though and don't even seem to care about our existence at all.
(Yes, the group of cool people looks exactly like the Cullens having lunch together and we felt exactly like Bella Swan, but at least for me no Robert Pattinson in the picture yet, so that's even worse. And don't pretend like you haven't seen the movie: we all had a Twilight phase #TeamEdward)
And that hurts, it really does: feeling excluded, like you don't belong with them because there's something wrong with you and you start having insecurities about yourself, your character, your physical aspect, your personality. This sort of paranoid thoughts never stop.
But here's the deal: being a part of the group does not matter, at least that's what I learned.
I'm the kind of person who doesn't like parties which are too loud, being surrounded by many people (yes, we're not so many but we, anti-party people, do exist and are not a legend like a shiny sparkly vampire, just to stay coherent to the theme).
I'm the kind of person who likes going for a hike in the early morning; who likes reading and writing and prefers a movie night instead of an all-night in the club.
And I don't care: I may have been excluded before, but sometimes it was more about what I thought about myself that excluded me and made me feel inappropriate.
What I've so far been learning in college is that it's not about fitting in, it's about being yourself and let other "outsiders" different from us be with us. To be outsider together.