Through charting different interactions and relationships, this book shows how Catherine and other characters change. First, Catherine is oftentimes embarrassed by David who can't always control himself because he has autism. Because of this, Catherine always feels like her brother is very weird and everyone will judge her because of David. When Catherine meets more popular kids, she tries to make David stay with her mother and not hang out with him. When going out in public, Catherine will make a list of rules, read them aloud to David, and try to make him promise to obey them. She also sometimes wishes that David could just take a pill and become a "normal" boy. When Catherine finally accepts David as who he is, she brings him to the school dance with her dad and grants his "wish" for grape soda.
Also, Catherine starts out as a relatively shy girl. After meeting Jason, she offers to make his speech cards, which help him communicate with others, and she adds colorful pictures to each card. This shows how Catherine has somehow opened a little to the world without trying to. She also runs around the parking lot, pushing Jason around while everyone is watching. Jason, unable to talk, has a special connection with Catherine as they run around the parking lot.
David, though unconsciously, matures a little as the book progresses. The book mentions that David has previously had problems at OT, but as the book goes on, this case does not occur near as often or as severe as the book described. Although he still doesn't act perfectly (as Catherine imagined), he eventually comes to apologize when he makes Catherine unhappy, and he comforts her when she feels down. David grows into a more responsible kid.
Jason, who can't speak, usually depends on his mother to do everything for him. After Catherine pushes him around the parking lot, He decides to get a new wheelchair with a joystick so he can do things on his own instead of waiting for his mother. Instead of waiting for his mother, he also takes walks with Catherine on the wharf and leaves himself on his own because Catherine can't take care of him. He also learns to restrain himself while Catherine brings her guinea pig for him to see. He changes into a more independent person.
