When Huck finds out that searchers are headed to Jackson Island to search for Jim, he doesn’t hesitate to return to Jim. He says, “They are after us!” when really, the searchers are after Jim. Why does he, too, flee down the river?

Huck is looking for adventure. He isn't yet giving Jim his loyalty, as he hasn't decided whether or not to help him or turn him in. Huck is still more concerned with himself than anything else..... staying hidden, escaping Pap, avoiding and "civilizing" other people might have in mind. Jim is company.... he's along for the ride.