@dt
No spoilers.
So you are in what Season 1. Book 1 Water.
Where Zuko is one of our main antagonists to go along with that one guy.
And Zuko grows as a character. Same goes for all three of the original cast.
Aang got better as soon as long as you ignore the GREAT DIVIDE!
Sokka got better as soon as the bad stuff happen to him.
Katara got better as soon as they run into another character.
And Iroh grows as well.