What does irony add to Edgar Allan Poe's "The Cask of Amontillado"?

A
strikingly ironic feature of Poe's story is the completely trusting attitude Fortunato appears
to show toward Montresor. It's partly explained by the fact that Fortunato is drunk, but what we
see, moreover, is the typical situation in Poe in which either a victim or a villain seems
immune to the ordinary processes of thought and rationality. Fortunato is similar in this way to
the king and courtiers in Poe's "," who never seem to realize, until it is too late
for them, that Hop-Frog hates them and is planning an extremely gruesome form of vengeance to
carry out against them.

Several smaller details in "" similarly
embody anwithout which the story might come across as a rather too
straightforward and even unsubtle tale of violent revenge. First, we are never given the
specifics of any of the "thousand injuries" Fortunato has supposedly inflicted upon
Montresor. The ironic absence of any description increases the sense of irrationality and even
terror...