Aang and Azula were naturally enemies due to the fact that they were on opposite sides of the war. Aang is the Avatar who was destined to end the war while Azula was the princess of the Fire Nation who set out to capture Aang. They first met in Omashu while doing a hostage until Azula and her team called off the exchange. They later fought again along with the rest of Team Avatar, Zuko and Iroh. It was then that Azula finally revealed her identity to Aang.
Aang and Azula later fought again while the latter was inside of a large mechanical drill that was penetrating the outer wall of Ba Sing Se. Aang managed to infiltrate the drill along with Sokka and Katara and damage it from the inside. When Aang later went outside to shut down the drill, Azula showed up and confronted him but Aang eventually managed to knock her out. Azula and her team would later infiltrate Ba Sing Se and attempt a coup. They fought Team Avatar underground and as Aang entered the Avatar State after mastering it, Azula managed to strike him down with a lightning bolt and kill him. Katara managed to revive him with spirit water but Azula believed him to be dead.
Most of the world thought that Aang was dead but Azula had a hunch that he might still be alive. This turned out to be true when Aang arrived during the invasion. She and the members of the Dai Li stalled him to keep him away from her father while the solar eclipse prevented everybody from firebending. Aang and the group later managed to escape. They later had one more encounter at the Western Air Temple where Azula finally managed to locate him.
Years later, Aang decided to help Zuko find his mother and Azula was with them too to help in exchange for her freedom from the mental health institute. Aang like many others did not trust Azula but was still willing to give her a chance because he is a peaceful and forgiving person. Aang even helped Azula with her luggage but confronted her whenever she misbehaved. Azula later called Aang and Katara stupid for being happy together as a couple.
Azaang is a somewhat popular ship among the Avatar fandom. Many ship it as an "opposites attract" ship in a similar manner to Zutara. Even though they are not opposite elements, their personalities are still opposite with Aang being a pacifist and Azula being ruthless. It is often shipped along with Zutara because it gives Aang a love interest. Some fans see the possibility of Azula reforming as a result of Aang.
- Aang is spiritually related to Azula due to the fact that he his the reincarnation of her maternal great-grandfather Roku.