One of the biggest mysteries in the franchise is the motive of Leon from Final Fantasy II. His home destroyed by the Empire, he is captured and though dead for a large part of the game, but instead he becomes the right hand man of the Emperor and gains a wealth of powers as a Dark Knight. Even after the Emperor's death, Leon chooses to simply take his place and it's only after a greater threat to the planet arrives that Leon joins your party.

So why did Leon join the Empire? Mind control? Secret dark side? Did he simply envy the Emperor's power?