What can be inferred from the story "The Cask of Amontillado" by Poe?

Edgar Allan Poe’s short story “The Cask of Amontillado” was published in 1846, less than three years before the author’s death. Set in Venice during the Carnival season -- traditionally a time of license --  it is narrated in first-person by Montresor, a man who believes that his acquaintance, Fortunato, has done him an unforgivable injury. Resolved to exact revenge, he plays on Fortunato’s vanity to lure him into the massive Montresor catacombs, and there walls him up alive.

What has Fortunato done to Montresor? We’re not told, but we have a few clues. As the two men descend into the catacombs, Montresor remarks, “You are happy, as once I was,” and also, "The Montresors . . . were a great and numerous family.” This suggests that at least in Montresor’s mind, Fortunato has ruined his happiness in some way that has to do with the continuation of his family. Toward the end, Fortunato begs to be released, remarking that “the Lady Fortunato” will be expecting him at home. Montresor responds to this with cold mockery. Could it be that Fortunato has married the woman whom Montresor loved? We cannot know for sure. It’s perfectly possibly that Fortunato’s crime exists only in the mind of the unreliable narrator.

What else can we infer? We’re told that Fortunato lives in a palazzo, that he is “a man to be respected and even feared,” that he is a noted wine connoisseur, and that his wife is Lady Fortunato. All this suggests that he is wealthy and powerful with high social status. By contrast, our narrator tells us that he himself appreciates wine and buys “largely whenever [he can],” implying that he does not always have the means to do so.

Beyond that, there is not a great deal of information that the reader needs to infer. Montresor tells us his own perspective of the events quite clearly (though we still need to decide how far to believe him.) It is Fortunato who is in the dark through most of the narrative. Montresor continually offers him hints about his true intentions, as well as putative opportunities to save himself, but Fortunato seems to understand none of these (though the reader does.) For example, take a look at the passage where he asks Montresor about his family coat of arms:

"I forget your arms."

"A huge human foot d'or, in a field azure; the foot crushes a serpent rampant whose fangs are imbedded in the heel."

"And the motto?"

"Nemo me impune lacessit.” [“No one injures me with impunity.”]

This may be a true description of the family arms, but it seems more likely to be Montresor’s invention on the spur of the moment, designed to taunt Fortunato indirectly about his companion’s intentions.

A few moments later, Montresor reveals the fact that he is carrying a trowel. Again, Fortunato has no idea what the true significance of this is. But any reader familiar with Poe’s works will immediately understand what is about to happen to the ironically-named Fortunato (“the fortunate one”).

Can you find other examples of dramatic irony in the conversation between the two men? What can you say about Fortunato’s Carnival costume of motley: that is, the traditional dress of a professional fool?