The first indication that he was too late was the massive column of smoke rising over the countryside. Next came the ashes, blowing toward him on the wind. Finally he flew over the charred ruins of what had once been the thriving city of Omashu. He could see people, running around the wreckage like ants, scurrying in their search for survivors. He estimated that about a quarter of the city had been destroyed.
The Avatar noted the sizable Earth Kingdom army camp located to the west of the ruins. Feeling confident the relief effort was well under way, he began his search for the perpetrators. It didn't take long.
After he passed the city, he could see a second column of smoke. This one, he noted when he got closer, came from what looked like the remains of a military unit. It had been so completely destroyed -practically buried in boulders- that Aang couldn't tell if it was airships or tanks. It was obviously Fire Nation, though.
With a tug of Appa's reigns, he directed the flying bison west, hoping someone could explain what he assured himself could only be a huge misunderstanding. The nagging voice at the back of his mind told him it was no mistake, reminded him of the breathless warning that had led him on this journey in the first place.
It had begun like any other day, with meditation in the Southern Air Temple, all quiet, but for the sound of birds and a novice clanking around in the kitchen. "Tashi," Aang thought, "No one else is that loud." She had come out of the woodwork after Zuko removed the century-old fire Nation bounty on airbenders. Most of her family were earthbenders, so she moved like a komodo-rhino in a teashop, and she airbent like the wind was made of rocks.
Giving up on any sort of intensely spiritual meditation, Aang lit a candle and focused on the flame and his breathing.
His concentration was broken by a crash. Then he heard the patter of feet on the stone floor, followed by Tashi shouting, "And just what do you think you're doin- Oh my!" Aang decided it was time to investigate and grabbed his glider. He jumped out the window and flew toward the source of the noise.
It was a red war balloon, looking incredibly worse for wear. Stumbling out of the cockpit was a man in green. He was breathing heavily and bleeding from a cut above his right eyebrow, probably from his less than perfect landing. Despite the dirt and blood, the Avatar recognized his old acquaintance, who was currently serving as an ambassador to the Fire Nation. Or more accurately, he recognized the moustache. "Haru!" Aang exclaimed, "What's going on?"
Haru, panting heavily, said, "Lord Zuko was killed - and then she went crazy - she took the throne - vowed to avenge - " He paused to catch his breath.
"Slow down! What happened to Zuko? How did Azu- "
Haru cut him off, the urgency in his voice increasing, "Going to attack Omashu - I came to warn you - barely escaped - hurry!"
Then Haru passed out.
After days of pushing Appa to his limits, Aang reached the caldera that housed the Fire Nation capital city. He landed in the palace courtyard. The guard had been doubled, maybe tripled. He usually only saw this much security on festival days. The soldiers eyed him cautiously, did not challenge him as got off Appa's back and strode into the palace. Whether the guards were under orders to let him through, or if they were simply more terrified of the Avatar than Azula, he couldn't tell.
Thinking of Azula made him wonder if she'd been orchestrating this attack, or if she just took advantage of the circumstances. He wondered where she was keeping Katara and the children. He was fairly certain they were safe - Katara's parenting style was half nurturer and half overly protective sabre toothed moose-lion. Even with Zuko gone - Aang quickly cut off that train of thought. He'd spent the whole trip telling himself it was a mistake, that he'd heard wrong.
He found himself at the doors to the throne room and pushed his worries aside. He'd have answers soon enough. He paused briefly to prepare for the confrontation to come, then threw open the doors.
The first thing he noticed was that, instead of the customary red flames, the front of the throne room was glowing blue. The red columns looked purple in the light, and the yellow dragon mural behind the throne was a sickening green.
Aang cautiously approached the figure on the far side of the forest of pillars. She was crouched over a bundle, laid on the floor. The blue light was emanating from there.
"What are you doing?" he shouted, running up to grab her hand, "Stop!"
"Let go of me!" demanded the woman, "I thought I made it clear, I'm not to be disturbed while- What are you doing here?"
As she spoke, he noted the dark circles under her blue eyes. "Wait, blue eyes?" he thought.
"Katara?"
/\/\/\/\/\
Author's note:
This story could follow any one of many excellent Zutara stories that have the following results: Zuko and Katara get married. Zuko is Fire Lord, making Katara the Fire Lady. They are in deeply in love (whether this happened before or after the marriage is up to you.) They have a couple of children.
It takes place fifteen years after the events of the TV series and ignores the comics and Legend of Korra.