
He loves watching faces and body language to make deductions, and he values the surfaces of things as the best source of clues for what's going underneath them. Consider the moments when Dupin suddenly interrupts the silence between them to say exactly what the narrator's thinking, out of the blue. Why does Dupin keep so separate from the rest of humanity? We think the key to solving this puzzle lies is in his interaction with the narrator. He and the narrator never go out during the day, but they love to walk around the Parisian streets at night, checking out people around them and guessing who they are and where they're from. But what he likes, way more than directly interacting with others, is looking at them. Dupin doesn't exactly hate other people – after all, he's willing to live with the narrator (and, we can't help but notice, on the narrator's dime). Neither Dupin nor the narrator seem like they belong to a book club, in other words. We get the sense the Dupin might not be the most social or extraverted of characters. We learn that Dupin spends what little money he has on books – he and the narrator become friends when they're both looking for the same volume at a library in the Rue Montmartre. As a result, he doesn't have to work for a living, but also doesn't have the social or political obligations of someone from an aristocratic background who still has lots of money. This means that he has a private income, but still has to live on a tight budget. Dupin comes from a great family that's fallen on hard times. Most of the details Poe gives us about Dupin's background and interests seem designed to show us that he's not great at playing with others. The thing about search engines is, they're not exactly social – we can't remember the last time we had a conversation with Google – and Dupin's no exception.
C AUGUSTE DUPIN WINDOWS
In other words, "The Murders in the Rue Morgue" is like a database of evidence – the three silver spoons, the twenty or thirty blood-smeared grey hairs, the windows locked from the inside – and Dupin is like the search engine that picks out what we need to know when we can't figure it out for ourselves. Remember, "The Murders in the Rue Morgue" is a new kind of story, less interested in depth of character than in engaging the reader in logic games. He's most notable for the role he plays in "The Murders in the Rue Morgue," for taking the many clues presented during the course of the story and assembling them into a whole.

After all, he's not really meant to be a rounded character.

We're not knocking on Poe's genius by admitting that Dupin isn't fully fleshed out as a character.
