Why is the sky blue? Why is the 草 green? Why do we hiccup?
I don't know. the only think that's important is that it is what it is. Zuko's hot. There is no specific reason for it; he just is. (Plus, he's, あなた know, a firebender. It's in the job description.)
i dont know!!! he just is!! and we want 2 keep him that way, rite? lets just let him be hot and 移動する on with ower lives. (not meaning 移動する on from zuko!)