Jonathan
Jemmy is both hero and protagonist of the book. He is a bright boy who was sent to the Jung's court to fill the role of Whipping Boy, a boy who would be punished whenever the young prince misbehaves - which is often. Jemmy is the son on working class parents whose main income comes from rat catching and this is how Jemmy assumes he will earn money when he is older. Jemmy is a nice kid who is well aware of the unfairness of his position although he is surprised to discover that he actually enjoys the sumptuous trappings of the palace and his life there even as a servant. He is keen to take advantage of any opportunities and to find a way to run away from the palace; he actually learns to read and write by paying attention to the lessons that the prince is refusing to pay attention to.
Jemmy is smart and resourceful, coming up with a clever plan to persuade the highwaymen to release the prince and calmly trying to see it through, conscientiously trying to keep the prince safe despite the way the prince behaves. He is empathetic and even starts to feel sorry for the prince because he has no friends. He is a very easy character to like and to root for.
Prince Brat
Prince Brat came by his nickname because he is an unimaginably spoiled, obnoxious and rude child who knows that nobody is allowed to punish him for anything. He seems to derive enjoyment from behaving badly enough to get Jemmy a whipping and his goal is for him to be whipped so hard that he cries, which stoical Jemmy never does. Much of his behavior is actually an attempt to get his father's attention as he feels that he is too busy with being the King to notice his very lonely child. Much of it is fueled by spite and a general lack of boundaries or demands on him to treat others nicely. Although at first he does not seem smart enough to follow Jemmy's escape plan he soon realizes that he can learn a lot from his whipping boy and starts to emulate him more. Prince Brat is very lonely and does not have any friends his own age at the palace, so he really envies Jemmy his friends and their obvious liking for him. At the end of the book his character has really transformed and he becomes a much nicer person because of his adventure.
Hold-Your-Nose-Billy
Billy is a highwayman who desperately wants to have a reputation for bring a terrifying and successful thief but in reality he and his sidekick Cutwater do not get particularly rich pickings and generally only manage to rob people of assorted junk items. He is a person with no morals and no brains but is tenacious in doggedly pursuing the two boys to try to recapture them. He is definitely a character who is a thoroughly bad lot.
Cutwater
Cutwater is Billy's partner in crime and is as inept a criminal as his friend. He is easily flummoxed by Jemmy's insistence that he is the Prince and by his plan in its entirety but is greedy and goes along with the plan so that he can get as big a ransom as possible. He is not very fit or athletic and that is why the boys manage to get away from him.
Betsy
Betsy is a gypsy girl who travels to fairs and carnivals with Petunia, her dancing bear. She is definitely a help to the two boys and gives the two highwaymen erroneous information which enables Jemmy and the prince to get a better head start.
