Ozai was extremely cruel, easily angered, aggressive, domineering, unforgiving, merciless, and insatiably power-hungry. It was implied that Ozai's deep-seated anger stemmed from a failed relationship with his own father, Fire Lord Azulon, possibly because Iroh, a kind, gentle, and cosmopolitan man, was favored over Ozai. Iroh noted several times that his brother is "not the understanding type," and that he had never known Ozai to regret, forgive or change his mind about anything. Ozai believed in harsh and brutal discipline, and no one was safe from his anger and aggression when he was displeased, not even his own children
Ozai's ultimate aspiration in life was to conquer the entire world, but in fact his desires may have been not for control but wholesale destruction to crush all resistance, as demonstrated in the series finale when he tries to destroy the Earth Kingdom for refusing to submit to his rule. He was willing to sacrifice members of his own family when asked just to stay in the grace of those above him. When ordered by his father Azulon to kill Zuko to teach him the pain of losing a son,Ozai admitted to Zuko that he would have gladly carried out the murder had Ursa not interfered. He also attempted to kill Zuko once again when the latter announced his intent to join the Avatar.
Ozai seemed to show little (if any) love or care for his own people. The day Zuko was banished Ozai seemed to support the idea of sacrificing new recruits to defeat a powerful Earth Kingdom battalion so he could get closer to controlling Ba Sing Se. When Ozai decided that he would use the power of Sozin's Comet to destroy the Earth Kingdom, he showed no realization or care that a great number of his people lived in the Fire Nation Colonies in the west where the attack would begin. Apparently Ozai views the deaths of his own people as minor sacrifices to become King of the World.
Ozai was mentally and sometimes even physically abusive to his children. While he may have tried to be a good husband and father at one point, as implied by Zuko's flashbacks to family vacations on Ember Island, his anger and lust for power degraded his relationship with his family. He believed skill and accomplishment determine worth. This allowed the naturally cunning and talented Azula to rise to the position of his favorite child. He expected nothing less than the best from her, thinking her a Firebending prodigy. This expectation put a great amount of stress over Azula, forcing her to become a perfectionist
At first, Ozai remained neutral due to his bending neing taken away by Avatar Aang after the Sozin comet.
But until now, recently, the socerers and scientists of the Org, including Maleficent herself, are trying to restore his power. Padro Lodo has an idea, but he believes it may prove fatal if it used very often.