An archtype is defined as...
...an original model of a person...upon which others are copied...universally recognized by all.
Edgar Allan Poe is considered by many to be the father of the detective story—because of stories like "The Purloined Letter." This was an example of one of what Poe called...
...‘‘tales of ratiocination,’’ which helped define the conventions used in Arthur Conan Doyle's Sherlock Holmes detective stories...
At the same time, the abiding popularity of Poe rests undoubtedly in his mastery of the horror story—like an early Hitchcock or Stephen King. Poe's stories are masterpieces of the macabre and remain highly anthologized in high school and college textbooks.
As a master at creating chilling horror stories, Poe was responsible for creating the archetype for some of the most interesting and frightening villains ever put to paper. One of these fascinating "psychopaths" is Montresor in Poe's "The Cask of Amontillado."
Montresor is archetypal of the criminal sociopath—the "Trickster" and the Devil: he harbors no guilt for his plan to kill his victim—or regret afterward.
Montresor concisely states that he has been insulted by Fortunato, though he never specifically mentions why. This might be the case to puzzle the reader, but I believe (because Poe was such a genius) that no reason given because there is no reason...it is a result of his insanity. He notes...
The thousand injuries of Fortunato I had borne as I best could, but when he ventured upon insult I vowed revenge.
(Fortunato allegedly has hurt Montresor many times.) In the second line, he addresses his audience, writing to those (a group—not "he") who know him; in sharing this narration, he seems unafraid of censorship for what he has done. Soon after, however, he admits that he cannot risk being caught. The ideal outcome is to punish, but not be caught.
I must not only punish but punish with impunity.
It is erratic that he announces to others he will have revenge, but now notes that secrecy is absolutely necessary. This may be another sign of Montresor's lunacy. He is also maniacally cunning: he plans each step carefully so as not to alert his victim:
...neither by word nor deed had I given Fortunato cause to doubt my good will.
The depth of Montresor's hatred is evident in his ability to smile in Fortunato's face while dreaming of his demise.
I continued...to smile in his face, and he did not perceive that my smile now was at the thought of his immolation.
Montresor wants Fortunato dead and wants him to suffer. Montresor is the archetype of a madman—calm and sane to the onlooker.
Fortunato is the classic fool. In countless horror movies, there is the sacrificial lamb, going to his/her death even as the audience knows he should not open the door, get out of the car, or go outside—but he still does.
Fortunato has a weak spot:
He prided himself on his connoisseur-ship in wine.
His first instinct tells him that Montresor cannot be right:
Amontillado, A pipe? Impossible! And in the middle of the carnival!
He ignores it. Fortunato is egotistical:
Luchesi cannot tell Amontillado from Sherry.
(Fortunato infers that he is the expert.) He is also inebriated:
He accosted me with excessive warmth, for he had been drinking much.
And even though he is walking unsteadily, Fortunato drinks more:
A draught of this Medoc will defend us from the damps.
Montresor is the criminally insane murderer; Fortunato is the silly fool.