Avatar: The Last Airbender Season 3 Episode 12 : The Western Air Temple

Zuko follows Aang and his friends to the Western Air Temple, seeking to join their group. There, Zuko desperately tries to prove to them that he has changed for the better. It is only after Zuko helps save them from Combustion Man that he receives their acceptance as Aang's Firebending teacher. However, Katara refuses to trust Zuko and threatens to kill him at the sign of any treachery.