Odd Man Out

So you have Bob, who goes off to see Alice and the rest of his circle of friends at school. But something feels...off, whenever he hangs out with that group he feels less important than the others in the eyes of his peers. In other words, he believes he is the expendable one of the group. This generally comes in two flavors:
 * Type I: Bob thinks he is the unwanted member of the group, but they decide to keep him with them anyway. Depending on how idealistic or cynical the story is will affect whether or not Bob's suspicions are correct. Generally, this has an optimistic ending, where Alice uses The Power of Friendship (sometimes The Power of Love) to show that she or the group actually does care for Bob.
 * Type II: This one may do away with Bob suspecting anything altogether. Here, the group really does think of Bob as expendable or unwanted, and usually has sinister intentions for him.

This character is likely to be a loner (though whether or not this is by choice varies), but if he is ever in a team, then he is most likely going to be The Lancer or the Sixth Ranger. He may be uneasy with teamwork if he is Type I (Justified if he is a suspicious Type II).

Live Action TV
 * In Supernatural, Castiel is a Type I, at least until his Day in The Limelight.