The next two episodes are a two-parter in which Zuko and Sokka form the most unlikely duo imaginable in order to liberate Sokka's girlfriend, Suki, and Sokka's father from a maximum security Fire Nation prison. After the group licks its wounds, Aang and Zuko must return to the source of all firebending in order for Zuko to regain his firebending abilities and to kick start Aang's firebending training. Despite the fact that tensions are running high, the current Avatar and his teammates cautiously take Zuko into the group. After several seasons of buildup, Zuko has decided to join Aang in order to help Aang overthrow his father and bring peace to the world. In the process though, Aang and his friends gain an unlikely new ally named Zuko, the son of Firelord Ozai.

As events usually unfold in Avatar, nothing really works out quite the way it should, and Aang must flee the Fire Nation in defeat.

Unfortunately, Ozai is nowhere to be found in his palace, and the time for the eclipse is running out. In 'The Day of Black Sun', Aang and his allies sought to strike the heart of the Fire Nation at its weakest point - when a rare solar eclipse stops all firebending abilities.

Watch avatar the last airbender book 3 episode 13