Not really an AU but, I've been thinking about my idea for an ATLA/avatar story.
Set during the time of (young) Guru Laghima, it would follow the story of the Avatar and her older sister. They are from the earth tribes, and have to flee their home after a strong, nonbending general calling himself the King of Earth and his army kill their parents.
The older sister, Sisi, is a 13 year old (at the beginning of the story) earth bender whose family had a stronger connection to the spirits than most. Sisi had been learning wood carving from her mother and earthbending construction from her father when the army destroyed their lives. She eventually grows into the person who invented the bending and solstice locks scattered through the various temples around the world, a feat which earns her the name "Lockbender".
The avatar, Mimi, is 6 at the start of their story, only just starting to learn earthbending. She is found out as the avatar because she liked to play with fire as well, able to make the fire and rocks around her dance from a young age. As she and her sister slowly travel the world, Mimi masters earthbending, then the other elements.
Laghima is a young, cocky, 16 year old airbender in the beginning, out on a nomadic voyage to learn about the world and the spirits that inhabit it. He finds the young sisters and likes to travel with them as he learns from the various places they visit.
Cheeks is Mimi's animal companion, an Iguanaparrot who they found injured. She likes to eat berries and carrots, and she picks up words to parrot relatively easily (and then just says "Berries please berries please" over and over)
The first book, Earth, is mostly slice of life of them travelling and becoming friends for 10 years until Mimi is a master earth bender and ready to learn other elements. Laghima is on and off, visiting temples and meditating with spirits a lot more than his companions. He also makes sure the two young girls are safe from danger, scouting and making sure they avoid the growing Earth army. The finale is them fleeing the Earth Kingdom, as the Earth King is crowned in the newly built Ba Sing Se.
The Second book, Fire, the companions enter the fire kingdom, and Mimi begins her fire training. Sisi, in barter for their stay, starts putting her construction and woodcarving abilities to work, helping to build and reinforce the temples, and gaining her name of Lockbender. Laghima meditates at all the temples, and floats for the first time. This book ends with Mimi being declared a master of firebending in only two years, and Cheeks picking up some fire related swear words.
Book 3, Air, the companions go to the Western Air Temple. As Mimi works on air bending and struggles to get past some blocks, Sisi works on improving the integrity of the upside down buildings. Laghima is made Mimi's part time teacher and is recognized as a Guru by his people. He hasn't yet mastered the state of mind for permanent floating, though is consistently floating with meditation. During this time, they also visit the other air temples regularly so Sisi can check the construction and install the giant airbending locks. It takes Mimi 3 years to master airbending. This season ends with the Earth king finding out about the avatar, and quietly dispatching a team to find and capture her, as the Earth Avatar is one of his citizens and therefore should listen to him.
Book 4, Water. The companions, still with Laghima, head towards the small southern water tribe to learn water bending. On the way, they instead discover some other water benders, a young new tribe in the middle of a swamp. Mimi starts to learn water bending from the swamp benders, and Laghima communes with the (while younger, still large and old) banyan grove tree, and finally learns what he needs to be weightless always. Sisi meets a swamp bender girl named Rocha who decides to join the companions (they're gay, Harold). A short bit through the book, they pick up travel to the Southern water tribe to complete Sisi's training, having gained all they could from the swamp. In the meanwhile, the earth king's team are getting ever closer. With half the book left, they complete the water training, the fastest of the elements, and are captured by the earth king's forces.
then plot, plot plot, it ends with Sisi sacrificing herself so Roche, Laghima and Mimi can escape. Mimi is a quiet avatar who spends the rest of her years trying to protect others from war. Laghima becomes the wise floating guru we hear about. Roche holds the memory of her wife dear, and retires to the banyan grove swamp where she spends years strengthening the spirit of the tree.
It's revealed also that the writer of this history is an old Mimi, with Cheeks also looking a bit grey on her shoulder (parrots live forever), looking out upon a peaceful Western Air Temple. With a small lock designed by her sister on the outside of the journal.
