Quote: I surrender with honor.
Azula is
Zuko's older sister. When they were young, Azula was always playing tricks on
Zuko, and favored her father,
Ozai, becoming the Fire Lord instead of
Iroh,
Ozai's brother.
Iroh's son died in battle, and when the Fire Lord of the time died, his dying wish was that
Ozai become the fire lord instead of
Iroh. Since then, Azula has become quite powerful, as she was pampered even more with
Zuko continuing to suffer. She doesn't make a big debut until the end of first season. She plays a major role in the second season,
chasing after
Zuko,
Iroh, and the
Avatar and company.
Some time in second season, she fights Katara, Zuko, Toph, and Aang, and severely injures Iroh, her uncle. In fact, Iroh even appears like he would die, but in the next episode it shows him bandaged up and awake. He is being tended to by Zuko and Iroh, and later starts to teach Zuko about the nature of the lightning moves of firebending and teaches him to redirect Azula's attacks.
Overall, Azula is brutal and ruthless, traits she inherited from her father.