Water is the element of change.
Earth is the element of substance.
Fire is the element of power.
Air is the element of freedom.

Sibling bonding time that has probably never happened. I interpret this as innocent brother-sister bonding time, that’s just my opinion.
I know the autor of this draw and even in the description she says it was meant to be that, as an innocent bother and sister bonding time.

I still totally think an animator drew this frame like this on purpose. They like Makorra.
Whenever Zuko tries to be intimidating, there’s generally a pretty standard reaction.
Zuko, buddy, ILY… but you’re really not nearly as cool as you think you are.
……THEN it occurred to me that this is how they all end up like right after the laugh
It’s true! I guess he showed them all…
That’s my baby for ya