Tom Sawyer's best friends include Joe Harper and Huckleberry Finn. In The Adventures of Tom Sawyer, Tom's infatuation with classmate Rebecca "Becky" Thatcher is apparent. He lives with his half brother Sid, his cousin Mary, and his stern Aunt Polly in the (fictional) town of St. Petersburg, Missouri. In addition, he has another aunt, Sally Phelps, who lives considerably farther down the Mississippi River, in the town of Pikesville. Tom is the son of Aunt Polly's dead sister.
In Adventures of Huckleberry Finn, Tom is only a minor character, and is used as a foil for Huck, particularly in the later chapters of the novel after Huck makes his way to the Phelps plantation. Tom's immaturity, imagination, and obsession with stories put Huck's planned rescue of the runaway slave Jim in great jeopardy — and ultimately make it totally unnecessary, since he knows that Jim's owner has died and freed him in her will. Throughout the novel, Huck's intellectual and emotional development is a central theme, and by re-introducing a character from the beginning (Tom), Mark Twain is able to highlight this evolution in Huck's character.