"If you want to keep her interested, you have to act aloof; like you don't really care one way or the other."
"You really think so?"
"Oh, yeah. Also, Katara's a sucker for papaya fruit salad."
"But Aang told me she hated it."
"He likes her too, of course he'd tell you that!"
"That conniving little snit!"
"Yeah, so go over the plan for me, just to make sure."
"Okay. I give her a papaya fruit salad for breakfast, ignore and criticize her, call her 'Sweetness', correct her bending stances, insist on managing the money, feed her bad tea, make her wash Momo, since she loves him so much, and push her around every once in a while."
"Great. You go do that, Zuko, and I'll just go watch from that tree over there."
As Katara slapped Zuko for a particular comment he'd suggested, kicked him for shoving her, and froze him to a tree for stuffing papaya into her mouth, Sokka could not grasp how anyone ever thought of him as an idiot.
For him, everything was turning out just right.