Both Huck and Jim can be viewed as the heroes of Adventures of Huckleberry Finn.
But if the two characters are the chief agents of good, the loathsome Pap Finn is the novel's most pitiful and despicable character in terms of exemplifying the characteristics of a depraved, squalid world.
When Pap reappears, with hair that is "long and tangled and greasy" and rags for clothes, it is a reminder of the poverty of Huck's initial existence and a realistic representation of the ignorance and cruelty that dominated the institution of slavery and prejudice in America. Pap is suspicious of both religion and education and feels threatened by Huck's ability to read and exist in a world of Miss Watson and the Widow Douglass.
Pap's role as an abusive parental figure is disturbing but vitally important to the novel because it sets up a direct contrast to the heroic and caring Jim.