Ozai
Ozai is revealed to be a cruel leader. He is easily angered and merciless. His cruel personality could be due to his failure in his relationship with his father, Azulon, who always favored his older brother, Iroh, over him. Ozai would prove to be a heartless father to his own son,  Zuko, believing him a failure and even burning his face and banishing him. He even banished his own wife, though admitted later that he felt banishment was too light a punishment.  He has a lust for power, a quality shared by his daughter Azula. He favors his daughter over Zuko, seeing her as a firebending prodigy. The expectations Ozai had for Azula caused her to become stressed and paranoid, eventually leading to her mental breakdown at the end of the series.