We have an elderly Azula in a world where Ozai succeeded in conquering everyone. She finally hits her Villainous Breakdown with the realization that there is no way she can escape her impending death from old age, so she decides to go out in a blaze of glory, starting a war that will probably kill a good percentage of the world's population, and also set things up so that she'll be remembered as a hero who tried to stop that war.
Gian is a ruthless and sociopathicBounty Hunter, who doesn't care who is in charge of the world order or who his employers are, so long as he's paid for his services - which involve murder. He forces a rather meek young Earthbending slave to help him uncover the rebellion base, and kills her in cold blood simply because he had no further use for her. He's also revealed to be an Earth Kingdom man who essentially exploits his own people for profit, and admits as much to Jiazin without an ounce of guilt about it.
Magnificent Bastard: Azula and also Qing Xi. Both of them openly admit that they have no real trust in each other, and just trust the idea that there would be no advantage to either betraying the other.