Trying to puzzle out how this might happen, and hereâs what Iâve come up with:
Zuko exists a century earlier, but still as prince of the fire nation, and with the avatar cycle falling such that itâs the fire nationâs turn. For the sake of this story, letâs not move the rest of the family tree, and just say that this means he is son of Sozin, and older brother to Azulon. It has recently been revealed to the young prince that he is the avatar. The first Fire Nation colonies were established before Zukoâs birth, and his whole life heâs been hearing how one day his nation will reign supreme over all others, how this is destiny taking its course.
His father wants him to make a display of the avatarâs power to the Air Nomads, who are expected to be the most powerful opposition to the Fire Nationâs plans. Zuko agrees, eager to please his father and serve his country. He only learns as they are en route that by âdisplay of powerâ his father means, âkill them all.â Zuko doesnât want to be a traitor to his country, but he canât betray his role as the avatar, either. His nation may have a destiny, but so does he. He is supposed to provide balance between the elements, not bring about the destruction of one. He confronts Sozin privately, says he wonât do it. Sozin calls him a traitor, says heâs a sorry excuse for a prince and undeserving of the power of the avatar. A fight ensues, in which Zuko receives his scar and escapes into the storm on the back of his dragon companion, Fang.
The storm is fierce, but Zuko canât stop for shelter. He has to warn the Air Nomads. Of course, he doesnât make it. The storm overpowers him; he is frozen in the ice.
Aang is not the avatar, but still the youngest airbending master in recorded history. He and his compatriots put up a hell of a fight, but theyâre no match for the power of the comet. Aang narrowly escapes with his life, and only goes when heâs sure thereâs no one left for him to save.
The story is that Prince Zuko, the last Avatar, was killed at the air temple, and that with no new airbenders for the power to pass on to, the cycle has ended. Aang doesnât know what the prince looked like, and in his angriest moments, he hopes he was the one who ended the boyâs life. The power of the Avatar should never have been used that way.
Aang becomes a hermit in the hills of the Earth Kingdom, and spends his life giving shelter and food and hope to refugees who cross his path. He lives a hundred years after the genocide.
Heâs out gathering food when he sees it: far in the distance, a pillar of light, rising into the sky. A phenomenon that nature could never have created. And suddenly, he understands whatâs happened: somehow, the Avatar is out there. And Aang has lived a hundred and twelve years for a greater purpose than he ever knew.