The characters

Montresor

Montresor (if that’s his real name), our narrator, is Mr. Sinister. He’s the guy you don’t want to meet in an underground graveyard, or anywhere else. He’s a cold and ruthless killer. He not only enjoys killing, but also thinks it’s necessary.

As the narrator, he’s telling the story fifty years after it happened. However, he is also known as an unreliable narrator. The story is told from Montresor perspective. As such, it can't be known if he is speaking the truth. We only get his side of the story, which makes it unclear if he is telling the truth or not. In addition to being the classic unreliable narrator, on the surface, Montresor is a classically unsympathetic character. A sympathetic character isn’t necessarily character we feel sympathy for; a sympathetic character is simply a character we can relate to, at least on some level.

Critics have been arguing for a hundred years over whether Montresor is confessing his sins or bragging about his crimes.
Fortunato

At first glance, Fortunato seems easier to identify with than Montresor. It’s much simpler to relate to the victim than to the victimizer. But, in some ways, he seems even more foreign to the reader than Montresor. Part of this is because Montresor is telling us the story, and he doesn’t give us much information on his prey.

As you surely noticed, Montresor doesn’t tell us how Fortunato hurt him, nor how he insulted him. So we can’t really say whether Fortunato’s punishment fits his crime.

Fortunato is addicted to wine. He’s already really drunk when he meets Montresor, and he thinks the Amontillado can help him take it to the next level. Right up until the end, he thinks of Amontillado, and only Amontillado.

Whether he really hurt and insulted Montresor or not, he’s so insensitive, he doesn’t notice that Montresor is mad at him, something any fool can see. 

Being too trusting can be a weakness – if you hang out with guys like Montresor. Montresor says he made sure Fortunato had no reason to doubt him. But still, Fortunato should know better than to follow a masked man into a catacomb.
The Montresor family

When Fortunato comments on how big the catacombs are, Montresor implies that all the bodies in the place are dead members of the Montresor family. There seem to be quite a lot of them. This is before we know Montresor’s name, but it’s implied that he’s a member of that family.

Is our narrator the last surviving member of the family? If so, what happened to the rest of the Montresors? Did he, perhaps, kill them all? Or maybe Montresor is lying and it’s not just Montresor bones in that massive graveyard. Maybe the Montresors were a family of killers, and the catacomb is full of unsuspecting victims, like Fortunato.

Maybe Montresor isn’t really Montresor at all. Maybe he murdered the last of the Montresors and then stole their name, so he could use it for his nefarious purposes. Montresor, if that’s his real name, makes clear in paragraph five that he is not Italian (though where he comes from is never revealed). So if he’s not Italian, what is his whole family doing buried in an Italian catacomb?

Ultimately, we don’t get any concrete information on the mysterious family Montresor; we have more questions than answers. In fact, Poe invites us to such speculations. They enhance the general creepiness of the reading experience, and make us suspect that Montresor, or whoever he is, is an even bigger villain than we might have thought.