Huck Finn has a lot of really interesting character traits that make him a very unique kid. He is clever; he anticipates his father showing up and wanting to steal all of his money, so to avert this situation, he goes to Judge Thatcher and tells him of the money, "I want you to take it," so that when his Pap shows up demanding his money, Huck won't have any to give to him. The Judge, having "bought" it off of Huck, will own, it, leaving Pap no legal rights to the money. Huck also demonstrates his cleverness in his awesome escape from the cabin in the woods. He stages the entire event to make it look like burglars robbed the place, killed Huck and dragged his body to the river, and then took off the opposite direction.
Huck is also ponderous, meaning, he thinks about things a lot before acting on them. He ponders the meaning of prayer before deciding,
"I couldn't see no advantage about it--except for the other people; so at last I reckoned I wouldn't worry about it any more, but just let it go."
He ponders slavery quite a bit throughout the book, and always decides to help Jim over his conscience bugging him about the implications of helping a runaway slave. Any odd thing he hears, or thing that he is curious about, he tests it out, mulls it over, and comes to his own conclusions.
Huck is also curious, adventurous, loyal, and funny. I hope that those thoughts help; good luck!