Azula discussion? *cracks knuckles*
One of the most fascinating scenes in the entire finale was, in my opinion, Azula's hallucination of her mother. I think that this scene provided us more insight into Azula's character than any other in the entire series. My favorite part is this section of the dialouge:
Ursa: "You're not a monster Azula - you're confused. All your life you've used fear to control everyone around you... like those two friends of yours - Mai and Ty Lee".
Azula: "Well, what other choice do I have?!!! Trust is for fools! Fear is the only reliable way. Even you fear me".
Ursa: "I don't fear you Azula - I love you"
I think that the point of this was to establish that the key essence of Azula's behavior prior to the finale was her belief that fear is the only reliable way - and that love and trust are for fools. Where that idea originated is hard to say - Ursa apparently shares a lot of the blame, but I think Ozai definitely played a role in it. This belief formed the core of a huge part of Azula's character. Once it was gone, she broke down.