Montressor explains that he has done the best he can to endure the insults from Fortunato but when he insulted his family he vowed revenge. He knew Fortunato's weakness and decided to use that. He meets Fortunato and tells him about a expensive bottle of alcohol and Fortunato is determined to go see it.
On the way to Montressor's catacombs, where he is storing the bottle, Montressor is insisting he doesn't need Fortunato and tells him to go back. Fortunato then feels the need to go which plays into Montressor's plan.
They reach the catacombs and once again, Montressor insists that Fortunato go back pretending that he cares about his health which in turn makes Fortunato feel safe and no need to worry.