The third paragraph of “The Cask of Amontillado” contains, in its obvious implications, a great deal of information about Montresor and Fortunato, showing that Poe was acting in accordance with his own dictum: "In the whole composition there should be no word written, of which the tendency, direct or indirect, is not to the one pre-established design."
The first two sentences of the third paragraph tell a great deal about Fortunato:
He had a weak point—this Fortunato—although in other regards he was a man to be respected and even feared. He prided himself on his connoisseurship in wine.
We know a lot about his connoisseurship, but it isn’t until the end of the tale that we see why Fortunato is “a man to be respected and even feared.” When Montresor has him chained to the wall, Fortunato tries using applied psychology to work his way out of the trap.
“Ha! ha! ha! – he! he! – a very good joke indeed – an excellent jest. We will have many a rich laugh about it at the palazzo – he! he! he! – over our wine – he! he! he!”
“The Amontillado!” I said.
“He! he! he -- he! he! he! -- yes, the Amontillado. But is it not getting late? Will not they be awaiting us at the palazzo, the Lady Fortunato and the rest? Let us be gone.”
Fortunato is pretending he thinks this is a jest. He does this in order to give his captor a pretext for releasing him if Montresor should change his mind about leaving him there to die. Fortunato is reminding Montresor that they are good friends and suggesting that they will be even closer in the future when Fortunato entertains him at his palazzo. Chances are that Montresor is rarely if ever invited to Fortunato’s home because of the difference in their social positions. (Such slights would be among those “thousand injuries.”) Fortunato knows his friendship is of value to Montresor, who would not have put up with so many injuries over a long period of time if he had not gotten something important in return.
The third paragraph of the story suggests that they both deal in luxury items such as paintings, statues, antiques, gemmary, and probably imported gourmet wines. No doubt Montresor has benefited financially from knowing Fortunato. They may have gone into partnerships on short-term acquisitions and sales of expensive items. Montresor might have even borrowed money from Fortunato and might have received finders fees for putting his friend onto lucrative investments.
Fortunato knows that Montresor’s greatest concern would have to be about being suspected of causing his disappearance. He is suggesting that people will remember seeing them together. When he asks, “Will they not be awaiting us?” he implies that a number of people have seen them together on the streets and assumed they were headed toward Fortunato’s palazzo. Also, in saying that Lady Fortunato and the rest are awaiting them,” he is doing more than implying that Montresor is to be welcomed into his family and elite social circle; he is suggesting that a search party of relatives, friends and servants might be organized that very night if Fortunato fails to turn up.
But Montresor took pains to establish that Fortunato was not "engaged" anywhere, so he won’t be missed until at least the following day when there will be empty streets and a cold trail. Montresor knows very well that if he released his captive now, Fortunato would probably have him murdered. Fortunato “is a man to be respected and even feared.”
The appearance of Fortunado in a jester's cap with bells led to the reader assuming he was a fool. His drunkenness also added to that assumption. He frequently stumbled and lurched, coughing when he noticed the nitre on the walls. Montresor's references to Luchesi, Fortunado's rival in wine knowledge, spurred the man onward. Even when Montresor tried (ironically) to get him to turn back, his arrogance in his wine judging ability led him to his doom. Only when the unfortunate man was nearly entombed did the reader feel any sympathy for the man. Poe's choice of a name for this character was the ultimate irony. There was nothing fortunate about his demise.