Montresor is considered an unreliable narrator because his opinion of Fortunato is biased. Montresor feels greatly wronged by Fortunato, but the exact wrongdoing that Fortunato has committed is never clearly mentioned in the story. As a result, readers cannot comprehend or agree with Montresor’s extreme form of revenge, which actually makes readers sympathize with Fortunato. In addition, readers do not have any background on Montresor, so Montresor’s sanity is questionable, considering he formulates and carries out an elaborate plan to entomb and murder someone who insulted him. -plato