Jackson's island
Huck picks up Jim, a runaway slave, while they are both trying to escape their respective situations. Huck finds Jim hiding on Jackson's Island while he is trying to avoid his abusive father and decides to help him in his quest for freedom.
Huck and Jim argue about English and French. Huck wants to learn French to look educated, while Jim argues that English is more important due to its widespread use in America.
Huck promises Jim that he will not reveal his whereabouts or help anyone looking for him while they are on their journey together. Huck assures Jim that he will keep their friendship and plans to help him escape to freedom a secret from others.
Huck is taken to an island in a nearby swamp by a house slave assigned to him to see a "swarm of water mocassins". A little suspicious, he goes anyway out of curiosity and some distance into the swamp is told to "go on ahead I've seen it before" or some such whereby he finds Jim asleep and is reunited. The Grangerford family slaves have provided for Jim and hidden him out in the swamp. The raft was found hung-up on a snag and Jim had gotten it back, reprovisioned it and was waiting to get back on the river with Huck. -roundabout
Huck doesn't turn Jim in because Jim in Huck's first TRUE friend. Jim is also the only "family" Huck has ever had that cares so much about him and will protect him.
Huck found Jim, a runaway slave, in the swamp when he went to check on the water moccasins. Jim had run away from Miss Watson, who was planning to sell him, and he was hiding in the island's swamp to avoid being captured.
Jim is one of the main characters in the book, to not have him in it would make the book boring, just to have huck running around from aunt polly would be interesting but it would not be the same. The dead man in the book in the floating house is later revealed as pap.
He wanted to protect him from the knowledge. Also, internally, he knew that if Huck didn't have a reason to be hiding out on the island, and later to head towards "free territory" than he himself would be out of luck.
Huck arrives at the Grangerford house after getting separated from Jim during a fog. Jim goes downstream in the raft, while Huck goes ashore and wanders into the Grangerford family's property. He is taken in by the Grangerfords and treated with kindness.
He told Huck that Jim had been sold as a runaway slave!!!
In 'The Adventures of Huckleberry Finn,' Huck learned that Mrs. Loftus' husband was going to use a gun to capture and turn in his friend, Jim for the reward money. While she was compassionate toward Huck's plight as a runaway child, she had no such compassion for a runaway slave.
Huck plays a complex role in discussions with Jim. He is both a friend and protector to Jim, helping him navigate their journey down the river while also grappling with his own internal conflicts about society's views on slavery. Their discussions often involve Huck challenging his own beliefs and learning to see Jim as an equal human being.