Ozai and Zhao were never seen directly interacting during the series but the two have interacted before. Zhao was always one of Ozai's most loyal officers and had a high rank. When Ozai burned Zuko's face during an Agni Kai, Zhao watched from the audience and smiled. By the time that the series started, Zhao had been promoted to lieutenant. While he was hunting for the Avatar, Ozai ended up promoting Zhao two more times. During the siege against the Northern Water Tribe, Zhao was killed by the ocean spirit La. Ozai blamed his brother Iroh for his death and considered him a traitor for going against Zhao's plan to kill the moon spirit.
Zhaozai is a popular slash ship in the Avatar fandom. Many fans ship them together because Ozai divorced his former wife Ursa and Zhao was never known to have been married to anybody. Some people feel that Ozai and Zhao do not deserve anybody but each other since Ozai was an abusive father and Zhao killed the moon spirit. Others felt that they belong together because Zhao was loyal to Ozai and Ozai felt betrayed by Iroh when Zhao died.