Mr. Rigby is the Leviathan's bosun, which makes him the guy in charge of all the midshipmen. He's sort of like Deryn's boss, and he's one of those loud, blustery, in-charge types who has a heart of gold—like a tough coach who expects a lot from his team, but really loves them too. He gives Deryn and the other midshipmen a hard time, pushing them to be their best by yelling things like, "'This is a combat drill! Get climbing, Mr. Sharp!'" (11.7). Deryn clearly likes him, since she leaps into thin air for him when he's shot during the Leviathan's first battle of the war.