Dee shoved his hands in the pockets of his ruined leather coat and set off down the narrow path. He hated it when they did that, dismissed him as if he were nothing more than a child. (32.46)
We think it's hilarious to see a dangerous, 500-year-old magician pout like a little kid. Age is relative, it seems, because although Dee is older than Sophie and Josh, he is centuries, and even millennia, younger than the gods and goddesses he interacts with. Because of his youth, he still gets no respect.