At first, A Separate Peace presents the classic struggle between young anarchy and old, established rules. This plays out at a boarding school, where the rules indeed seem restrictive and unwarranted. But other systems of rules soon emerge, as even the poster child for adolescent rebellion lives by a set of "commandments." Rules, then, do not always restrict and control. We learn that the best indication of a character is the rules that he lives by and the principles he follows.
In A Separate Peace, identity is defined by the rules which one follows and those one chooses to break.