Zuko

Zuko is a firebender from the series Avatar: The Last Airbender. In the first two seasons and half of the third season, Zuko is the main enemy to Aang and his friends.

Seasons One And Two
In seasons one and, Zuko is trying to hunt down the Avatar. By season two, his uncle and him are refugees from the fire nation, but as soon as Zuko spots the Avatar again, he has to choose between turning against Iroh and going home with Azula, or staying with his uncle. He chooses to go with Azula.

Season Three
In season three, Zuko is still living at the fire nation with his family. But then, on the day of the eclipse, Zuko 'betrays' his family and his country because he knows that his destiny is to help Aang learn firebending.

Sozin's Comet
By now, Zuko has taught Aang just about all the firebending moves he knows, and Aang is ready to face the Fire Lord.