In Theory

A/N: I am willing to bet my last buck that Zuko's felt like this at least once. This is set a little around The Western Air Temple.

The curiosity is addictive, and so Zuko watches.

The watching is painful, and so Zuko hurts.

The hurting is unpleasant, but Zuko's been used to it all his life.

Katara serves him last, ensuring that he gets the least to eat. He doesn't complain, long being used to starvation. He sits quietly, watching the others.

Toph, the Earthbender, talks openly, apparently unaware or unconcerned about the others' awkwardness to him. Zuko likes her for that, and is thankful. But his attention stays to her for very little, and then goes right back to Katara and Sokka.

They're sitting beside each other, shoulders almost touching. Zuko thinks it's unnerving. He can't imagine sitting that close to Azula and not feeling scared. They seem calm, happy almost. How can that be?

The group loosens up a bit. The Avatar starts to talk, recounting a tale about his old Air Nomad friends. Zuko smiles a bit at the punch line. Once more, he looks at the siblings.

They're laughing openly, their expressions benevolent. Their postures are relaxed. When the mirth dies down, Zuko finds no trace of suspicion or malice in their eyes.

At one point, Sokka says something stupid, and Katara rolls her eyes. She retorts with a sharp comeback, but it's good-natured and joking.

Dinner ends and they sleep.

The next day, the siblings are arguing. Katara is yelling at Sokka, who apparently did something wrong by tipping over the vessel of boiling broth she was cooking. The Water Tribe warrior shouted right back, trying to tell her that he simply didn't see it, and anyway, Katara was a Bender. She could simply bend the broth to safety.

Zuko watches, expecting Katara to blast water in Sokka's face. After all, being a non-bender he wouldn't even be able to defend himself. But all she does is shoot him a dirty look and clean up the mess.

Later that evening, Sokka apologises for being clumsy, and Katara apologises for yelling at him.

By dinner, they're friends again.

Zuko's training Aang when Sokka comes to the temple, bleeding profusely. He'd gone hunting, and had been attacked by a platypus-bear. Everyone panics.

The Fire Price watches Katara's horrified expression, and watches how she forces him to lie down. He watches how she heals him, bandages him, and takes care of him all day and night. He sees her worry and concern, and he can't relate to it.

That night, he lies awake, thinking about such relationships. In theory, all siblings should be like that: teasing, temperamental and caring.

Zuko closes his eyes. His mind drifts to Azula.

A/N: Felt right to just end it here. Hope you liked it. Thanks for reading :D