At the start of the novel, Huck Finn feels different from the people in his community. This is clear in the interactions between Widow Douglas, Miss Watson, and Huck. Huck explains how life continued after he returned to town safely at the end of Tom Sawyer:
"The Widow Douglas she took me for her son, and allowed she would sivilize me; . . . The widow she cried over me, and called me a poor lost lamb . . . She put me in them new clothes again, and I couldn’t do nothing but sweat and sweat, and feel all cramped up. . . After supper she got out her book and learned me about Moses and the Bulrushers, and I was in a sweat to find out all about him; but by and by she let it out that Moses had been dead a considerable long time; so then I didn’t care no more about him, because I don’t take no stock in dead people."
Huck, who is used to living with his uninterested, drunken father, isn't used to having rules. He isn't used to having to be clean or having to learn about the Bible. In fact, he says that he doesn't want to learn the biblical stories because they are about dead people. He can't imagine that these old stories can relate to his life. His new clean clothes are uncomfortable and restrictive. He simply feels different from these women who claim to want to help him. Huck feels separated from the rule-oriented people in his hometown.
Later, he is kidnapped by his father and taken to a cabin in the woods. At first, he likes this, thinking he has escaped the strict rules of the town. However, he is still isolated. He is left for many hours alone as his father goes out each day. Later, his father soon becomes abusive, threatening Huck's life with a knife in one of his drunken fits, and he wants to escape. He chooses to run away. He makes a plan to leave; first, he kills a wild pig and throws the blood of the pig around, as though he has been killed. Then, he runs away to a small island on the Mississippi River, Jackson Island. Now, Huck is more isolated than he was before. He is separated from all townspeople while he lives alone on the island.
Or, so he thinks. Soon later he runs into Jim, a runaway slave (and therefore, another isolated character) on the island. They end up fleeing down the river together, taking a log raft that they found and repaired for their travels. Still, Huck continues to feel isolated from others. Huck believes that he is doing something wicked by rafting away with Jim. After all, Jim is a slave who belongs to Miss Watson; he is her property. Doesn't that make Huck a thief? He imagines that most good people would turn Jim in. He thinks he is a criminal for traveling with Jim.
He continues to feel more different and isolated from others as he recognizes Jim's humanity. At one point, Huck pulls a prank on Jim, lying to him and saying that Jim had only imagined that Huck got separated from him. When the sun comes up the next morning, there is evidence of their separation (leaves and a smashed oar). Jim makes Huck feel bad when he tells him how he was sad, and even in tears, when he thought they were separated forever from one another. Jim points out how mean it was that Huck lied to him, making him feel silly by pretending they were never separated.
When Huck realizes how upset his prank (his lie) made Jim feel, he says,
"It was fifteen minutes before I could work myself up to go and humble myself to a [slave]; but I done it, and I warn’t ever sorry for it afterwards, neither. I didn’t do him no more mean tricks, and I wouldn’t done that one if I’d a knowed it would make him feel that way." (ch. 15)
Here, Huck begins to recognize that Jim is a valuable human being, just like any other person. He begins to feel more isolated from the majority of society that doesn't see slaves as equally valuable humans. Yet, in some ways he begins to feel less lonely because he has Jim. Though distant from most of the people they meet on their travels, Jim and Huck become companions for one another throughout the rest of their journey. Throughout much of the novel, Huck Finn feels separated and isolated from the people he interacts with on his travels.