Premise: Thomas "Tom" Sawyer is the title character of the Mark Twain novel "The Adventures of Tom Sawyer" (1876). He appears in three other novels by Twain: "Adventures of Huckleberry Finn" (1884), "Tom Sawyer Abroad" (1894), and "Tom Sawyer, Detective" (1896).
Hypothesis: Tom Sawyer is prominent in every novel he is in.