How do the narrator's spoken remarks to Fortunato compare with his internal feelings for the man in The Cast of Amontillado?

There is definitely a tension; Montresor makes overtures of friendship and comradery with Fortunato while all the while despising the other man and plotting his destruction. Indeed, it is through his friendly disposition that Montresor lures his target into the crypts—greeting him warmly and claiming to have acquired "a pipe of what passes for Amontillado, though I have my doubts." As Fortunato fashions himself as a wine connoisseur, Montresor is in this manner able to entice Fortunato into joining him.
As they walk, Montresor offers his companion wine to drink in order to further lower his ability to defend himself. Thus, the two head deeper into the catacombs, with Montresor continuing to maintain his deception of friendship. When they come to the destination where Montresor intends to entomb his now thoroughly inebriated victim, Montresor enchains Fortunato and proceeds to bury him alive.