Zuko x Siobhan: Flaming Hearts

Siobhan is a fire bender who ends up joining Team Avatar on their mission to take down the Fire Lord for good and she becomes best friends with Aang, Katara, Sokka, Toph and Zuko.

Zuko is a fire bender and he was the banished prince until his own father had been defeated by Team Avatar causing for Zuko to become the new Fire lord of the Fire Nation and everybody had gotten busy with their own lives as Aang and Katara have started to build Republic City, Sokka had gone back home to the Southern Water Tribe, Siobhan had became a fire bending teacher to the younger children and Zuko was busy with his own royal duties.

Many years later, Team Avatar have grown up into adults and they meet a new threat as they begin a journey of finally bringing the air-benders back to their world. Along the way, Siobhan discovers some things about her biological parents and her own childhood as she starts to fall in love with Zuko and Zuko starts to fall in love with Siobhan.