okay so this isnt exactly a lone idea it does latch onto the ATLA storyline perhaps an alternative universe but I do really like the idea of Aang having some secrets from his past about his people….it isnt ever really explained with what I have learned so far

My eyes wouldn’t open but all around I heard screams, terrible screams of the dying. The heat from flames and the warmth of fresh blood puddles on the cobblestones beneath my stumbling feet. I couldn’t scream and I couldn’t see, as I slowly opened my eyes smoke clouded around me. Water filled my eyes and I waved away the toxic fume, crashing noises of falling rock and the silence of some screams far off.
Blood… Sweat… Tears… Children ran around holding open wounds and crying out to their mothers. Monks took stances and tried to use their Airbending to put out the flames, it was in vain. As another catapult shot the rock of pure flame towards them their cries of agony rung through the walls remaining. People running away, aflame and slowly dying. I could see the general of them, no not a general…Firelord Sozan.
He walked up to me and grabbed my neck roughly; his general came to his side and pulled out a list. “Annaliese, 15 and sister of the Avatar, Aang.”
I almost gasped at the mention of my brother…he had run away three days ago…Monk Gyatso said that he left a note but never shared it. I didn’t know why Aang left, I had guessed that the whole Avatar thing was too much for the little guy to handle, he was strong and smart… A master of Airbending yet still 12 years old, those Monks told him of his power before he was ready and now…well it was almost lucky that Aang became so miserable he had to get away. Now that he was gone the Fire Nation wouldn’t get him, wouldn’t kill him like everyone else…
What would happen to him…would he survive or would the Firelord find him? Would he hide for the rest of his days, the Southern Water Tribe or Kyoshi Island…both safe and close by.
Would he ever learn the other elements? Would he act in hatred to avenge her or his people? Usually the monks taught the boys and the nuns taught the girls at separate temples. No one is allowed to know of their true family until they are 18 and allowed to become a monk or travel… The only reason she or her brother knew of each other was because of Monk Gyatso, he brought them to their mother, and she was in Omashu…Aang had met Prince Bumi there for the first time, a royal Fire Nation family also passed through and a boy from there got lost…. Kuzon…he was nice to me. He acted funny, blushed lots and easily befriended Aang….
Could Kuzon know or have known of this ambush? I know…this is the genocide of the Air Nomads…my people, peaceful and free…innocent monks and nuns. Not even a military force, not a weapon ever created by their people…yet we are to be remembered in ashes and charred bones. There is only one thing I want…my dying wish…Protect Aang…please spirits…my brother is young, innocent and unprepared. Protect him…