[He closes his hand and snuffs the fire before she can touch it. He does not trust you with fire, Selphie. Not this Sokka or any other.]

Well, as the Avatar, it's my job to master all four bending styles and then maintain balance in the world between the four nations, as well as be the mediator between our world and the spirit world. It's a pretty important job, overall. Only one Avatar in the world.