Four years later
The Fire Nation was finally flourishing. Zuko sat at the throne of the Fire Lord, tracing the patterns in the worn wood. He'd thought about getting rid of the throne, seeing as it contained mostly bad memories for him, but some of the older advisors had talked him out of it. They said it was too imbued with tradition and culture for the Fire Nation, and that some of the older citizens might see it as a betrayal. But he was finally helping his people, and helping his country. He was bringing the Fire Nation back to where it used to be, before his grandfather harnessed the power of the comet to start the war. And Mai had finally left him alone.
Sometimes he wondered what the rest of the freedom fighters were up to- he heard many things about Aang. As the Avatar, he was all over the place, though Zuko hadn't actually talked to Aang in over a year. He'd had some correspondence with Sokka as well, though not of late. The only person he'd heard nothing from was Katara, not since he'd taken over as Fire Lord.
Suddenly, he felt a change in the air. As Fire Lord, he was connected to the entire Fire Nation, and he could feel major changes in its environment. This one was indeed major- and it felt like a fire. Not the normal kind, but the raging, all-encompassing kind of forest fire that would eat everything in its path with tongues of flame. He sprang from the throne, and ran outside of the palace to the courtyard. There, he paused, closed his eyes, and took a deep, cleansing breath. Then he expanded his chi outward in an ever-widening circle. There! It was on the south side of the island- and it was big. Really big. His eyes narrowed. There was also no way it had started naturally. It was this kind of self-destructive terrorism that had been slowly spreading. He needed to find whoever had started this, and deal with them. Preferably harshly. But now, he needed to get to the south side of the island, and fast. Because if he didn't get there, it might well destroy an entire town- or kill a whole lot of people. So he started running.
Katara was in the sky, drifting aimlessly. She'd spent the past few months mostly as water, learning more about her own powers than she ever had before. She could become any form of water, communing with all the other droplets around her, and urging them to form cohesive particles, or split into smaller pieces. And then she felt the heat of a raging fire. She frowned- or rather, she thought of frowning. Her face was dissolved into the cloud around her.
She might have let it burn, but she could tell this fire wasn't natural. It needed to be put out, or people might be in danger. Hell, people already were in danger. She gathered up her cloud body, and surrounding clouds, and pulled together over the fire, then crashed down with torrential rainfall, though she held the lightning back. The fire was extinguished almost immediately, but she let the rain fall for some time longer, making sure all the remaining embers were put out. She also let herself fall to the ground with the rain droplets, re-forming her body once she hit the earth. Then she stood, silent, watching the rain fall.