Montresor, the narrator, has already outlined his rather intense criteria for successful revenge. He has also named his enemy, Fortunato, as one who has harmed him and insulted him in so many ways. He's even said that he can now smile at his enemy because he is imagining the man's "immolation"—complete and utter destruction. However, Montresor has not told us exactly how he plans to achieve this destruction, and so when he seems so happy to run into his enemy, we might be somewhat surprised. He says,
I was so pleased to see [Fortunato] that I thought I should never have done wringing his hand.
When what happens in reality differs from our expectations, irony is created, and, therefore, it is ironic when Montresor seems so glad to see Fortunato, the man we know that he hates. We later learn that this is all a part of his plan to achieve his revenge.