Huck has his daily freedoms denied to him by the well meaning but suffocating Mrs. Watson. Huckleberry Finn, the young hero and narrator behind the book, feels like a prisoner in Mrs. Watson's house with her insistence that he conform to the expectations of society. These social expectations according to Mark Twain, is what takes away our freedom and joy in life.
Huckleberry Finn Huck is also the prisoner of an alcoholic father who beats him and curses everyone, "Then the old man got to cussing and cussed everything and everybody he could think of, and then cussed them all over again to make sure he hadn't skipped any" (Ch 6) In other words, by virtue of being white, Huck's father who was a rotten drunk was free to do and say whatever he liked. (In sharp contrast to Jim the slave.) To escape the paradox Huck would seek refuge in nature and Tom's company, "Then I slipped down to the ground and crawled in among the trees, and, sure enough, there was Tom Sawyer waiting for me." (4) To Huck, Tom Sawyer is a symbol of freedom and adventure. He enjoys the time they spent freely expressing themselves.
By contrast Jim, who is the first of a long line of runaway slaves, became a runaway to avoid being sold by his mistress to new owners in New Orleans.