When the sun came up and morning arrived, Aang, Katara, Sokka, and Smith walked out of the cathedral and Paris hailed them as heroes. The crowd lifted them up and implied that they would never be forgotten. The other three decide to accept Smith into their "family".
The four of them stuck around Paris. After another week, Quasimodo, Phoebus and Esmeralda returned. The archdeacon and several citizens told them exactly what happened. They felt eternally grateful, seeing as how the same thing happened to them one year earlier.
The archdeacon told them from his perspective while Aang and the others were in town. When they retuned, Quasimodo and the others were inside the cathedral waiting for them.
"Aang, I'd like to meet the people I told you about", the archdeacon said.
Aang looked at Quasimodo.
"I'm Aang. Are you Quasimodo?"
"I am. Many have already told us what you and your friends have done for Paris. And for Notre Dame. We all wanted to thank you somehow."
"How?"
"You and your friends aren't Roman Catholic, are you?"
"They aren't. But I already am", Smith said.
"Right. But you Aang and Katara and Sokka, aren't?"
"No. We're not."
"Do you want to be? I think you would considering how you all risked your lives to save this place."
The three of them agreed. That night, they were baptized by the archdeacon. They now had a newfound perspective on the world. But they also knew they couldn't stay. They had to find a way back to their own world. Aang may changed personally, but his world still needed him as the Avatar.
The next morning the four of them left Paris. Before they left Notre Dame, Quasimodo gave them each something to remember them by.
"Here"
"What this?", Aang asked.
"It's a crucifix medallion. This is sacred. As long as you wear it, it should protect you from the evils you may encounter."
The medallions were fairly large.
"Thank you", Aang said as he hugged Quasimodo.
Aang, Katara, Sokka, and now Smith left Paris together to go looking for a way to return home.