[Appa responds with enthusiasm, bounding in her direction, wet hair shaking water everywhere. He makes as if he's going to jump up on the witch, but Sokka makes a sharp noise and the sheepdog immediately responds by sitting, tail wagging and tongue lolling.]

If there's anything I can do to help, you know I'm glad to do it. I could search for whatever you might need, or do research, or even try to talk to Snape about what he learned... [Not that Sokka would get any response.]