Kizuna doesn't exactly sit still on his shoulder at first either. She keeps craning her neck or switching shoulders until she realizes they're headed towards the training building. Then she calms down a bit because that is absolutely a place that Mommy brings her to a lot. Rob seems to understand the problem and maybe she will be there.

...she isn't, but she is in the general vicinity and she spots Rob on the way there.

"Have you seen--?? Oh. Oh, you found her." Zuko looks and sounds so relieved it almost seems uncharacteristic.