Luchesi is a kind of insurance for Montresor. He brings Luchesi up whenever he wants to keep Fortunato distracted – like right before he “fetter[s] him to the granite.” But again, Montresor doesn’t really need to evoke the name of Luchesi. Fortunato is not only drunk, but also willing to do anything to get to the Amontillado.
Luchesi is a plot device, used to helo drive the action. He is the rival of Fortunato in wine tasting. He is an insurance of Montesor because he knows that Fortunato is willing to do whatever it takes to get to the Amontillado.
