AN: Dedicated to Spring, who said a thing over on Little Zuko which sent me spiraling down a chain of what-if's that ended, about twelve logic steps to the side, with this premise. So if you like it, blame Spring! All the blame.
1. Fire Lord
They let Zuko out of his cell because the world is ending. The Fire Lord has been defeated, the guards tell him, even though the Fire Lord was here just this morning. Tall and strong, alive, gloating one more time on his way to burn the Earth Kingdom down.
That was yesterday, they tell him. It isn't the worst slip of time he's had, and it doesn't make their words any more believable.
"How?" His voice is raspier than usual. They didn't bring him water when they came. One of the guards cringes like he expects to be lit on fire for this oversight, which tells Zuko everything he needs to know about their expectations for him. They let him out anyway. This tells him something else.
It was the Avatar, of course. Somewhere over in the Earth Kingdom, and reports are conflicted on whether Ozai is dead or a prisoner or something inexplicably worse, but he is definitely defeated.
His father has been defeated, and his fourteen-year-old sister is—is banishing everyone, is insane, she hasn't killed anyone (yet) (today) but it isn't for lack of trying. They've abandoned a whole wing of the palace to her—
No one gave the order to set him free, Zuko realizes. No one wants him; they just need him. This takes him longer than it should to understand, but the guards are speaking so fast and no one has really talked to him in weeks, and—and he stops at the prison entrance, and doesn't hear anything for a while.
He hasn't seen the sun in weeks, either.
"Your Highness?" one of the guards tries on for size. Tries again: "...Your Majesty?"
Fire Lord Ozai has been defeated. Fire Lord Azula is insane. Fire Lord Zuko is crowned by sunset, the nation's fallback heir.