Zuko disrespected Ozai by speaking out against one of his general's plans. As a result, Ozai challenged his son in an Agni Kai. However, Zuko did not want to battle his father, which Ozai saw as a sign of weakness. Therefore, the Agni Kai resulted in Ozai burning Zuko's eye, as a punishment for lacking courage. After Zuko's pathetic display during the Agni Kai, he was banished, and was only allowed to return under the condition that he bring back the Avatar.