I think Crisis Core already explained his background well enough. He got crazy after he discovered the stash of documents and books. Basically, it truth shocked him and he started to become evil.

Back to topic.
Has anyone here played the DOS version of Prince of Persia? Aww man, it was effing awesome. As a little girl back then, I found it rather challenging and of course that is also thanks to my poor reflex. The memorable scene was how easy the "Prince" dies. A careless run and jump could easily caused him to die. Bad timing of running past the gates also contributed to his death. I spent hours replaying the game.

And of course there were other memorable scenes in other DOS games as well such as Lost Vikings and Wolfenstein. Horrendous graphics + lots of fun gameplay = Memorable.