Colonel Miles Quaritch: Insanity's Edge?

[Patrice Maire]

Quaritch had lost his humanity (not sanity..that's different) before he got to Pandora, then when he got there and almost was killed (likely by a Thanator) that kind of changed his mind set.
He was just waiting for the right time to be able to cut loose and hose down everything on the planet that got in his way. Once he saw Jake was the one attacking the 'dozer, he realized that he no longer had Jake under his command. He lost it a little bit there. When a man changes from being focused to frenzied, your mind is lost. He thought the battle would be cut and dried, then when things started to go bad ('Weapons free!') he started to get a little frantic. Once he realized that Jake was the root of the problem he was bent on revenge with a frenzy.
He's like Ahab, bent on a self defined revenge that seems insane and in any other situation would be considered crazy. His reactions escalated with the events that prompted his actions.
(See the article I posted with the Stephen Lang commentary on Quaritch.)