Since its release, Avatar: The Last Airbender has, developed a reputation for having a deeply complex and at times tragic story. While ATLA's tragedies are easy to forget due to the often whimsical nature of the show, the world of ATLA has been immersed in a constant state of war since the first fire nation attacks a hundred years earlier.
Source:https://www.cbr.com/most-tragic-atla-characters-who-deserved-better-lives/