in part five Justin how does julien bully jack

One day, Justin leaves the Pullman house at the same time as Auggie's friend Jack, and stays with Jack until the bus comes. Jack borrows a dollar from Justin to buy some gum. While Jack is crossing the street, Justin watches as a couple of kids walk by and sneer at Jack. He asks Jack if they are friends of his; Jack says that they are just some jerks from school named Julian, Henry, and Miles. Jack explains the war going that is raging over his friendship with Auggie. Justin advises Jack to tell a teacher about his problems, but Jack refuses. Jack gets on the bus, and as Justin walks to the subway station he spots the three kids again and warns them not to mess with Jack, tapping his fiddle case because he knows that they do not know what is inside.