Why does the dog’s action affect David so deeply? Consider his last prayer (p. 185) as well as his final understanding of the dog’s behavior.

The night David makes his escape, he tells King to stay behind where he can be sure of being fed. David makes his way through through the tunnel and out onto the road, which is now clear of snow. As he thanks God for helping him see what he had to do, he becomes aware that he's being followed. Believing it's the farmer coming after him, he quickly hides, but happily realizes that it's King! David keeps going, happy in his faith in God and with King. "The long winter had passed," narration comments, "and he was going down to meet the spring."

King is David's prtector, and he not only defends him from an attack by the farmer... he later follows David when he escapes. When the two of them stumble upon an outpost manned by "them," King sacrifices his life so that David can and will go free. King is an embodiment and/or manifestation of the narrative's thematic consideration of the value and importance of free will.