Finn (also known as Finn the Human and formerly Pen in the original short) is the main protagonist of the series Adventure Time.
The Ice King does not really hate Finn and Jake, as he only fights with them because they are opposing each other in terms of morals. He frequently tries to be friends with them (in his own, misguided way) and has willingly made alliances with them. In the episode "Still" The Ice king freezes Finn and Jake so they can have "bonding time". It was shown in Hitman that while Finn and the Ice King are rivals, they are not enemies, and don't harbor any real malice towards each other. The Ice King made it clear that he doesn't want to kill Finn- the most he would do is punch him in the belly and make him vomit up his lunch. At worst, they are battling rivals, as Finn openly disapproves of the Ice King's habit of stealing princesses and causing mischief. At best, they are playful rivals, even friends. In "Holly Jolly Secrets Part II," the Ice King has a locket with the pictures of Finn and Jake. Near the end of the episode, the two are shown snuggled up side-by-side by a roaring fire, wearing ugly Christmas sweaters. Finn's attitude towards the Ice King has softened since discovering the tragic secret of his origin, and his compassion for people in distress outweighed his petty squalls with him enough to be his friend.
Where I got this: http://adventuretime.wikia.com/wiki/Finn__________________________________________________________________________________