Disclaimer: I do not own Avatar: the Last Airbender, it's owned by its creators Michael Dante DiMartino & Bryan Konietzko and Nickelodeon.
After the Harmonic Restoration Movement ended, Avatar Aang, Fire Lord Zuko, and Earth King Kuei worked together to form the United Republic of Nations. Yu Dao was the model city and became the capital of the new nation and was renamed Republic City.
Team Avatar, as Sokka called it, disbanded after the United Republic of Nations was created. Aang left to rebuild the Air Temples. Sokka and Katara stayed in Republic City. Toph stayed as well, and she worked on teaching benders to metalbend and created a school for it. Zuko and Suki returned to the Fire Nation; Suki went with Zuko as part of his guard.
Zuko and Mai broke up during the Harmonic Restoration Movement because Zuko was keeping secrets about meeting with his father. Mai realized Zuko loved his secrets more than her, even though she loved him more than she feared Azula.
Aang and Katara also broke up during this time. Aang loved being an Air Nomad more than having a future with Katara. He became interested in an Air Acolyte named Xing Ying, who turned out to be another airbender.
Three months after Aang and Katara, and Zuko and Mai broke up Suki visited Sokka in Yu Dao.
"Sokka, it's good to see you," said Suki. They hugged.
"It's good to see you, too. How have you been?" Sokka asked.
"I've been doing fine. You know I can take care of myself. But I am concerned about Zuko," Suki replied.
"I know you can take care of yourself. I was just worried because I care about you. What's wrong with Zuko?" Sokka asked.
"He's been pretty depressed ever since his break up with Mai, but he won't talk to anyone about it. I sort of feel responsible for their break up, and I'd like to cheer him up," said Suki.
"Hmm, Zuko's not the only one depressed about a break up. Katara's been moping around ever since Aang broke up with her. She even talked about going home, but I told her that Gran Gran wouldn't want to see her like this. Usually, she would reply with a snowball at me, but she just sighed and agreed. I haven't seen her waterbend in while either," said Sokka.
"That doesn't sound like the usual Katara. I wonder what happened," Suki said.
"I don't know, but maybe seeing you will cheer her up," said Sokka.
"If not, we could always go visit Zuko. You or Katara might be able to get him to open up and talk about what's bothering him more than I can," Suki said.
"Hey, that's not a bad idea," said Sokka. "I think I have an idea of how to convince Katara to see Zuko."
"It's not something like telling her that Zuko's going to restart the war or go after Aang are you?" Suki asked with raised eyebrows.
"You'll see," said Sokka.
Stay tuned...
AN: Yu Dao won't become Republic City until later.