Who is The Friend from Cold Fire and what is their importance?

The "friend" is a manifestation that appears to Holly and Jim when they go to the windmill. He claims to be responsible for sending Jim on his missions, as well as helping him to forget the existence of a 'friend' until he felt compelled to bring Holly to the windmill. Although he seems to be a benign presence, the self proclaimed male entity is also petulant and argumentative.