If anyone cares, I have a Secret mechanism in my eternally-being-written-game, which is a little different from the hermit's. Each character has a secret, which is known by the character but not by player. The player picks a question, such as What crime did I commit or Who are my parents. It is then up to the GM to answer that question at some point in the story. The goal is to have a big reveal to a secret from the past, which is as surprising to the PC's player as to the rest of the group. The game as a whole is very cooperative story telling, and so while the players get to tell some of the story of the adventure, the GM tells some of the story of the characters.