What is the main conflict in Wandering Willie's Tale by Walter Scott?

"Wandering Willie's Tale," by Sir Walter Scott, first appeared in Scott's 1824 novel, Redgauntlet. The tale is not directly part of the action of the novel; it is simply a story told by one of the characters to another, and in fact is merely the most developed of such stories contained in the novel. Several other times in Redgauntlet the action stops while one character tells another the story of his life or of one specific event. In this case, Wandering Willie, a blind fiddler, tells Darsie Latimer, a young man traveling in the Border region of Scotland, a cautionary tale to warn him to be wary of whose company he accepts on his travels, for even a friendly traveler may turn out to be the devil in disguise.