Answer:
By withholding information about Fortunato's condition.
Explanation:
The short story of "The Cask Of Amontillado" by Edgar Allen Poe tells the story of a friend taking revenge on another friend. Montresor had been planning to exact revenge on Fortunato for all the 'supposed' insults that he had done.
Montresor thinks that Fortunato had been insulting him and doesn't even realize it nor does he apologize for them. So, he planned on taking revenge, luring him with a favor of tasting wine in his family's catacombs. Once there, he instead chained Fortunato to a pillar and built a wall, closing in on the space, thereby locking him altogether to die. In the scene of the final acts of him building the wall, the author had till now only gave the description of Montresor. His actions had been described and the focus was only on him. But with the sudden shift to the character of Fortunato, giving us a glimpse into his condition, the author gave us a surprise in his decision of including the condition of Fortunato.
