Yeah. Thinking about it now it's almost like he's a completely different character in between games. In Halo 2 he was manipulative with how he made everyone in the Covenant believe that activating the rings would lead to salvation instead of death. He was a good villain and was smart. In Halo 3, he seems more like a maniac. He tries to do whatever he can to activate all the rings at the Ark. There may be reasons for why he changed so much between games. One I can think of is because he started to become even more crazy at the end of Halo 2, if you remember him talking in the level High Charity when the Grave mind was taking over the Covenant ship he was saying "Mercy and Regret are by my side" or something like that, even though Mercy and Regret were dead. He may has well have gone insane in Halo 3. The only change that doesn't make sense when playing both games is the change in voice, but that's because of the voice actor from Halo 2 being replaced.