Like I said in the first part: some of these are AU, and some are not. I'll give you a hint: check the title again before guessing. Chapter 1 never happened, for example, and only in a story that didn't happen would Ozai be the father he never was..
Five Buildings Zuko Didn't Burn Down
The Fortress of Pan
The forest rebels' hideout, occupied territory, age 16:
In mid-winter Zuko's retinue moved steadily through the Northern Earth Kingdom waters on the trail of the flying beast, and stopped in Yangtai mere weeks after the three-way encounter with the pirate crew and the Avatar. What had once been a prospering Fire Nation settlers' village at the mouth of the Yangtaiko river delta had become a flooded cesspool of mold and eroded landscape. Some vicious fool blew the damn, and all the money Zuko hoped to spend to re-supply his ship was as good as mud to them. They needed every scrap themselves to survive, and an exiled prince had no power to regrow crop fields or build up houses.
When it was clear the town of Yangtai had nothing to offer, General Iroh sent hunting parties into the nearby forests with orders to secure enough wide game to tide them over until next landfall. Zuko spent the hours looming over maps and charts of the Earth Kingdom, plotting the possible routes his quarry might take on what already appeared to be a steadily Northward trek. He was still in the cabin, hand cramped and neck strained, when his uncle delivered the news that two squad returned with fresh provisions and one squad had disappeared entirely.
Prince Zuko led another team into the forest to search out the missing soldiers, and after warnings from the villagers and hours of tracking they discovered the truth: a troop of children had robbed the prince's hunting party and made a hostage of his first lieutenant. Zuko knew they were only children, but they killed like assassins and they bargained like pirates. He tracked them through the night, he rescued his officer, and as soon as he got the chance he burned their thatch tree houses to ash on the wind.
Of the mad young man—who could have been the prince's twin in age and anger—Zuko did not speak, but there was blood on his broadswords when Iroh saw him again. They buried three soldiers the next morning. The prince watched the ceremony with the poisoned arrows he'd dug from their chests snapping like reeds between his fingers.