In "The Cask of Amontillado," the narrator’s insistence that Fortunato should turn around and go back out of the vault for the sake of his health is an example of dramatic irony:
“Come,” I said, with decision, “we will go back; your health is precious. 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—” “Enough,” he said; “the cough is a mere nothing; it will not kill me. I shall not die of a cough.”
Although the narrator presents himself in the passage above as caring and considerate of Fortunato, the reader is fully aware that he is anything but. Thanks to the narrator’s internal monologue as he relates the events of this story, which occurred 50 years in the past, the reader knows that the narrator’s real goal is to use reverse psychology to compel Fortunato to stay on the path—and therefore to exact vengeance upon him. The narrator even takes countermeasures to ensure his plans will not be interrupted:
There were no attendants at home; they had absconded to make merry in honor of the time. I had told them that I should not return until the morning, and had given them explicit orders not to stir from the house. These orders were sufficient, I well knew, to insure their immediate disappearance, one and all, as soon as my back was turned.
Thus, it must be understood that the narrator’s insistence on Fortunato’s health is specifically curated to produce the exact reaction he wants: for his enemy to choose the path towards his death himself.
As the narrator slowly bricks Fortunato into captivity in “The Cask of Amontillado,” Fortunato begs to be released in a moment of both dramatic and verbal irony:
But is it not getting late? Will not they be awaiting us at the palazzo, the Lady Fortunato and the rest? Let us be gone.” “Yes,” I said, “let us be gone.” “For the love of God, Montresor!” “Yes,” I said, “for the love of God!”
At first, Fortunato makes his request of the narrator in a lighthearted tone, with the expectation that he will certainly be released to meet the people waiting for them at the palazzo. However, what he does not know is that the narrator has been planning to trap and kill him for the duration of their encounter, making his initially lighthearted plea a moot point and an instance of dramatic irony. In fact, the narrator notes in his recording of the events that he went so far as to ensure the lack of any servants or attendants in the nearby vicinity, to better execute his vengeful plans. Additionally, the narrator’s response to his plea is full of verbal irony. He repeats Fortunato’s words back to him mockingly, with a double meaning: he agrees they should each get going, but the implication is that Fortunato should head to his death while he himself returns to the world of the living. His repetition of “for the love of God!” is the final nail in the proverbial coffin, sealing Fortunato away forever—and himself away from God.
