Zuko's banishment from the Fire Nation was a result of him speaking out against a general's tactics during a war meeting. This led to a duel, known as an Agni Kai, with his father, Fire Lord Ozai. However, Zuko refused to fight his father, which was seen as a sign of weakness. As a result, Ozai burned Zuko's eye, leaving him with a permanent scar, and banished him from the Fire Nation. The only way for Zuko to regain his honor and return home was to capture the Avatar, a task he pursued relentlessly.