Hans changes as the story unfolds. Zusak uses flashbacks to also illuminate his character. Hans is your nondescript nice guy. This never changes. He is careful not to stand out but it's the little things he does, as well as the big, that make him the character readers love. I think Hans is a static character, he doesnt significantly change his personality through the book. Consider 1916 (flashback) during WW1. Hans's life is saved by Erik Vandenburg. Hans not only repays him by hiding his son Max but Max becomes a sort of son to him. When Hans feeds a starving prisoner a piece of bread, he is sent away. Even after he is injured at the front, Hans really maintains his humble kindness. He continues to do small heroic acts that he had always done. Remember when he painted over the anti-simetic graffiti? I think the point here is that throughout the profound changes that happen to Hans, he still remains the quietly heroic kind man that readers love.