Entertainment / Literature / Raisonneur: A character in continental literature whose purpose is similar to that of a chorus in Greek drama, i.e., this choric figure remains at a distance from the main action and provides a reasoned commentary about what takes place. However, a raisonneur doesn't necessarily sing like the chorus, and the character appears in other genres of literature (short stories, novels, poems) rather than in dramatic works. (French, 'Reasoner')
Search Google for Raisonneur: