Idea for a story/play/screenplay/etc:

A man isn't who he was, but doesn't remember how he became who he is. He doesn't like who he is, he likes who he was, and wants to get back to that, but can't. He is, irrevocably, who he is. But if he can understand how he became who he is, maybe he can make this life worthwhile too. Maybe.

Oh shit, I just wrote The Bourne Identity by accident.