Everything you need to understand or teach Dog Man by Dav Pilkey.
Dav Pilkey's graphic novel, Dog Man: Twenty Thousand Fleas Under the Sea, follows the adventures of Dog Man as he encounters Piggy, a villain who was a member of the Fleas but whose group is now identifying themselves as the Friendly Friends. Dog Man and his friends wind up being tiny so that they are forced to fight a mite. Petey learns that he does have friends who are willing to help despite his past mistakes, and they all agree that life is best when lived fully. The main themes of this novel are the effects of mistakes, the importance of friendship, and the roles of a character.