A:TLA is owned by Bryke, not me.
When Piandao arrived at the Order's camp on the outskirts of Ba Sing Se, Iroh greeted the younger man warmly. He had not seen his friend since before Zuko's banishment, but that was not the only reason that he was glad to see the other Fire Nation man. Piandao also potentially had news of Zuko. As the leader of the Order of the White Lotus, Iroh had been too busy planning the retaking of Ba Sing Se to be able to get into the city to listen to the news of the Fire Nation circulating among the soldiers stationed there. There were a handful of other people from the Fire Nation in the Order's ranks, but other than Jeong Jeong, none of them knew just how close he was to his nephew and Jeong Jeong was just as busy as he was.
That evening, after Piandao had had a chance to get settled in, Iroh dropped by the younger man's tent to catch up with him. After about an hour of exchanging stories of their lives since they had last seen each other—which had included some surprises, like the fact that Piandao had given some sword training to Sokka, the Water Tribe boy traveling with the Avatar—Iroh brought the conversation around to news of the Fire Nation.
"You're really looking for news of Zuko, aren't you?" Piandao asked.
"Yes," Iroh said simply. He didn't have to say anything more. Piandao already knew that he thought of Zuko as his own son.
"From what I've been hearing since the eclipse, you have every reason to be proud of him," Piandao said. "He disappeared from the capital during the eclipse and the rumors say that he ran off to join the Avatar. Given that he's been officially declared a traitor, the rumors are probably true. There's also a newer rumor that says he was involved in a recent break-out at the Boiling Rock."
"How did he end up there?" Iroh asked.
"I don't know," Piandao said. "It's entirely possible that he wasn't there. The break-out is a fact, but Zuko's involvement has only been mentioned in rumors."
As he left Piandao's tent and returned to his own, Iroh was only half-aware of his surroundings. The rest of his mind was occupied with what Piandao had told him. Zuko had changed sides. Zuko had joined the Avatar. Was he teaching the boy firebending?
As he went to sleep that night, Iroh's heart was lighter than it had been since that disastrous evening in the catacombs beneath Ba Sing Se.