In Edgar Allan Poe's short story The Cask of Amontillado, "Luchesi" is an unseen character used by the story's narrator, Montresor, as a source of leverage. Montresor, of course, is plotting his revenge against Fortunato for a series of unspecified insults. He knows, however, that his intended victim, Fortunato, is not a man to be taken lightly, even in the inebriated state in which Montresor finds him. He also knows, however, that Fortunato is a man of considerable ego and that the best way of enticing Fortunato into his trap is by appealing to his vanity. By suggesting that he, Montresor, will ask this unseen character, Luchesi, about the cask of wine rather than asking Fortunato, he knows that the latter will rise to the bait. This is strongly hinted at in the following passage from early in Poe's story:
“As you are engaged, I am on my way to Luchesi. If any one has a critical turn, it is he. He will tell me——”
“Luchesi cannot tell Amontillado from Sherry.”
This one reference to Luchesi by Montresor does the trick. Fortunato takes the bait, but Montresor must continue to dangle the name of Luchesi before his victim to ensure Fortunato remains on track to enter the dungeon that awaits. That is why, Fortunato having entered the cellar of Montresor's home only to experience a respiratory episode caused by the foul mold-infected air in the basement, seems on the verge of turning around the leaving the home, thereby upsetting Montresor's plan to murder him. In order to prevent any such occurrence, Montresor again plays the "Luchesi" card:
"You are rich, respected, admired, beloved; you are happy, as once I was. You are a man to be missed. For me it is no matter. We will go back; you will be ill, and I cannot be responsible. Besides, there is Luchesi——”
The continued references to Luchesi are employed to ensure that Fortunato remains sufficiently intrigued and vain so as to continue along the path to his doom. Luchesi is never seen, but his presence is certainly felt.