Outcasts fit into society as exactly what they are, outcasts. What we think of an outcast in modern times differs from the true definition. The actual definition is "a person who is rejected or cast out, as from home or society", referring more to a person actually exiled from a place. Today when we think of outcast, we think more of this guy:

It is safe to assume that today this kid would be labeled an outcast, either by himself or others. But when you think about it its not like society has taken this person and thrown his ass into a jungle, or a volcano, or something. He still exists within society and lives among everyone else, but still he could possibly qualify as an outcast. Although modern outcasts do not fit the defition I read, I'll just use them as an example anyway. Like I said before, these "outcasts" still exist within society, and they still fit in, but they fit in as outcasts. They are essentially normal people, but they either don't look normal or don't have normal ideals, so they fit in to a much smaller group, again still within society.