Zuko was the former Crown Prince of the Fire Nation. When he was young, his mother suddenly disappeared and his father ascended to the throne of the Fire Nation. At thirteen, his father challenged a young Zuko to an Agni Kai for speaking out of turn at a meeting where the young prince would receive a permanent scar on his left eye. For refusing to even fight during the duel, Zuko was exiled by his father. The only way he could return was if he captured the Avatar, which became one of his top priorities.