In Faulkner's The Hamlet, the Ratcliff allegory, who is the Devil?
Ratliff's allegory is the centre of the narrative. However, it is not woodenly allegorical in the sense that one might apply the Prince figure to a number of the citizens in Frenchman's Bend.
Most basically, the Prince would represent Jody Varner. More widely, the Prince represents Frenchman's Bend.
He is upset because the man with the straw suitcase has outwitted him in the trade of the man's soul. The man has done so by changing what is considered valuable in the trade.