What is Fortunato's role in the Cask of Amontillado?
Dressed appropriately as a jester (or fool) in his gaudy carnival costume, Fortunato plays the part of unwitting victim in Poe's classic story of revenge. Fortunato has at some point in time insulted his friend Montressor, who has cunningly planned to take revenge in a most severe manner. Unable to resist Montressor's offer of a rare bottle of amontillado--a dry Spanish sherry--Fortunato willingly follows Montressor deep into the family catacombs where he is left to die a lonely death among the bones of his killer's ancestors. Fortunato's fate is to pay the ultimate price for his unnamed slight against Montressor.
Fortunato is the unfortunate victim of the narrator, Montresor. We never find out any specifics of what Fortunato has supposedly done to Montresor, but we do know that Montresor hates him and plans to take terrible revenge on him.
Fortunato does not exhibit any fear of Montresor while they are together, prior to the final horrible scene. One thing we do know about Fortunato is that he is a wine connoisseur; this characteristic is how Montresor is able to lure Fortunato into the catacombs, by telling him that they will sample a choice Amontillado wine.