The story does not say why Fortunato insulted Montresor. In fact, there is doubt that there ever were any insults at all. They might have simply been a product of Montresor's imagination
Montresor is the one who kills Fortunato in "The Cask of Amontillado" by Edgar Allan Poe. Montresor lures Fortunato into the catacombs under the guise of tasting a rare wine, then walls him up alive as revenge for an insult.
Montresor has a conflict with Fortunato in "The Cask of Amontillado." Montresor seeks revenge against Fortunato for some unspecified insult, leading him to lure Fortunato into the catacombs with the promise of sampling a cask of rare Amontillado wine.
The narrator in "The Cask of Amontillado" is Montresor. He tells the story of his revenge against Fortunato for an insult he endured. Throughout the story, Montresor manipulates Fortunato into following him to the catacombs where he ultimately traps and walls him up alive.
In "The Cask of Amontillado," Montresor lures Fortunato into his family's catacombs under the pretense of tasting a rare wine called Amontillado. Once they are deep inside, Montresor chains Fortunato to a wall and walls him in, leaving him to die. This act is revenge for some unspecified insult that Fortunato has committed against Montresor.
In "The Cask of Amontillado," the main character Montresor seeks revenge against Fortunato for an insult. Montresor manipulates Fortunato's pride and ultimately leads him to his death in the catacombs. The conflict between the two characters is driven by Montresor's deception and betrayal of Fortunato's trust.
The inciting cause in "The Cask of Amontillado" is when Montresor reveals that he has been insulted by Fortunato but has been patient in seeking his revenge. This revelation sets the events of the story in motion, leading Montresor to plot and carry out the murder of Fortunato.
The unfortunate Fortunato dies.
In the end of "The Cask of Amontillado," the reader discovers that Montresor has successfully lured Fortunato into his catacombs, where he chains him and walls him up alive behind a brick wall. Montresor then reveals that he committed this act out of revenge for an unspecified insult that Fortunato had given him.
Montresor and Fortunato
The narrator of "The Cask of Amontillado" is Montresor. He tells the story of how he seeks revenge on Fortunato, ultimately leading to Fortunato's demise.
The Murder of Fortunato at the end of the story was the Resolution. The Problem began at the insult to montresor and it ended (or was Resolved) by His Murder.
Montresor and Fortunato