You and Zuko were children at this stage.
You were outside. Sitting by the fountain in the courtyard of the Fire Nation palace. You were braiding your hair while humming. You watched the water flow up from the fountain. It was very peaceful. Until it wasn't.
You were sitting by the fountain when all of a sudden, you get pushed in. You gasped. The water was cold. How ironic. You looked out and saw Azula laughing. You got out. Your clothes absolutely soaked. Then you felt a warm hand grab your and lead you away.
The hand in question was Zuko's. Azula's brother. He led you to his room. He handed you a towel and took some of his clothes out for you. You smiled at the gesture. He stood by the door and turned his back. To give you some privacy.
You giggled and started undressing. The room was mostly quiet. Except for the sound of wet clothes falling to the floor then fabric and metal rubbing against each other as you put it on.
After you changed, you tapped Zuko on the shoulder and he turned. You looked adorable in his clothes. They were a little too big for you, but it was alright. He wrapped his arms around you in a hug and you hugged back. The door opened but neither of you cared. It was his uncle Iroh that opened the door.