Montresor shows that he is obviously a sadist and that he is enjoying the success of the revenge plan he has been working on for a long time. In addition, Poe needed to fill up some time. After all, building a stone wall from floor to ceiling is not a simple task. Poe didn't want to spend too much time describing the arduous job of building the wall, but he didn't want to make it look too easy either. The real climax to the story occurs when Montresor snaps the padlock that secures the chains around Fortunato's waist. After that, as a good story teller, Poe wanted to conclude the tale neatly and adroitly. However, there was still the big job of laying tier after tier of stones, plastering over the wall with more of the same mortar, and covering the whole section as thoroughly as possible with human bones. Poe's story-telling genius can be seen in the way he manages to cover all this work in so few sentences. When Montresor takes a break from his work, it provides a break from the repetitious description of working with the mortar and stones;, and it also creates the illusion that more time went into the project without wasting additional words. The reader might well wonder how Montresor became so proficient as a mason that he was able to create a nearly perfect wall that appeared to be just a part of the natural granite walls of the catacombs. Montresor wanted to be sure that at no time in the future would anyone who might happen to be down there might notice the existence of an artificial wall and wonder what was behind it. Poe makes the task seem simple. But how many of his readers would be capable of doing such a perfect job--unless, of course, a reader might be a professional mason?
At this point in the story, Montresor has clubbed Fortunado on the head, knocking him out, and chained him to a wall. As Fortunado slowly regains consciousness, Montresor begins laying bricks to trap Fortunado. He pauses periodically when Fortunado moans in pain; Fortunado eventually wakes up and begins screaming.
I reapproached the wall; I replied to the yells of him who clamoured. I re-echoed, I aided, I surpassed them in volume and in strength. I did this, and the clamourer grew still.
This implies that Montresor is actively seeking to enjoy and mock Fortunado's predicament.
Thus Montresor is, by all means, a sadist; someone who takes pleasure in inflicting pain upon others. Were he merely concerned with exacting revenge upon Fortunado, he would simply brick him up in the catacomb and be done with it; yet he keeps pausing, checking, reassuring himself, and so on, all with the purpose of knowing that Fortunado has no chance of escape, and that Fortunado is aware of the long and miserable death that awaits him. In fact, it seems odd that Montresor doesn't take the opportunity to reveal to Fortunado exactly why he is doing this; the fact that Fortunado doesn't ask either lends some credence to Montresor's earlier claim that Fortunado's insult was the last straw that pushed him to commit this act.