Huckleberry Finn: He's the narrator of the novel. He's rebellious, opposing the ways of Widow Douglas, and preferring not to be neat and tidy all the time, and not following customs of the society. He seems to be more materialistic than religious, but he has a sense of adventure and is rather daring, as shown by him joining Tom Sawyer's gang or journeying down the river.
Tom Sawyer: He's Huck's friend, but is very dominating over his friends and especially influential over Huck, who believes many things he says, such as rubbing a lamp to get a genie. Tom is very imaginative, and comes up with crazy plans of looting and killing people, but everything, according to him, should be done 'by the book', such as pirate books. He too is adventurous like Huck.
Pap: He is Huck's cruel, disgusting, and drunk dad who is illiterate and has no respect in society.
He represents the worst of white society, and doesn't want Huck to be anything more than him (i.e. literate, well-dressed, etc.)
The story is set in mid 1700s in America. First few chapters are in St. Petersburg, Missouri, where Huck lives with Widow Douglas. Other parts take place in Pap's cabin and Jackson Island. The rest is set on the Mississippi River. The atmosphere, for the most part, is adventurous, with Jim and Huck escaping the city and living life independently. There is a fear factor at many times, however, because they are afraid of getting caught or attacked by robbers, or getting lost on the river. Overall the atmosphere is tense, with few parts being funny.
Huck vs. Pap: Pap is drunk, beats up Huck whenever he can, takes money from him, and doesn't want him to be educated. Huck...