It's a straight-up ATLA riff on my part, actually.
AANG: Yay! ... wait, what exactly is that?
ZUKO: It's some kind of mystical gemstone.
AANG: Well don't touch it!
ZUKO: Why not?
AANG: I'm just very suspicious of giant glowing gems sitting on pedestals.
(ZUKO picks up the gemstone.)
Things proceeded from there in about the manner you'd expect anything involving Zuko making a decision of any kind to proceed in.