It seemed that just as soon as Zuko had wormed his way into their group, he declaring that he’d lost his bending. It struck her as the most amusing sort of irony, and she scathingly told him as much.
And yet—she found herself wondering, if he did have some sort of ulterior motive to joining their group… why admit so readily that he’d lost his bending? Aang needed a firebending teacher, and they tolerated Zuko because he could fill that role. When he stopped being able to bend, why tell them at all? He could have easily staved off any of them knowing with some excuse. Late at night, alone and feeling the restlessness the moon awoke in her, Katara frowned. If she thought she could have understood him once, she had been proven sorely wrong. It was no different now. Breathing out curious thoughts of Zuko, Katara closed her eyes and tried to sleep. Who knows why he did what he did?
After he went off alone with Aang, they both came back having discovered—and rediscovered—firebending. Now he could finally get around to teaching it. Katara grudgingly had to admit that it was impressive to spectate them practicing. Being able to actually watch Zuko bend as he demonstrated katas, rather than in relation to how she could avoid and counterattack, gave her an odd new appreciation for how he moved. It made her uncomfortable when she catch herself enjoying watching. Whatever he told them all about being changed and on their side now, Katara couldn’t so easily dismiss all his past actions. She remembered Ba Sing Se with painful clarity, and promised herself she would not be so easily fooled by him again.
It wasn’t long after that when he disappeared again, this time with Sokka.