A Separate Peace explores the difficulties with understanding the self during adolescence. (When we say it like that, it sounds like buckets of fun, doesn't it?) Identity is complicated enough as the narrator enters adulthood in a time of war, but a difficult friendship with a fellow student and rival leads to a further confusion of identity. Attempting to alter identity serves any number of purposes, from escaping guilt to living through others to dealing with insanity, but these attempts ultimately fail; the characters are forced to deal with their selves, actions, and personal identities.
Gene and Phineas's friendship is threatened when Gene alters his own identity to be more like Finny.
Gene and Phineas develop a closer friendship when Gene alters his own identity to be more like Finny.