C. Auguste Dupin able to read the mind of his companion, the unnamed narrator of all three stories. Poe created the Dupin character before the word "detective" had been coined. The character laid the groundwork for fictional detectives to come, including Sherlock Holmes, and established most of the common elements of the detective fiction genre. Dupin is from what was once a wealthy family, but "by a variety of untoward events" has been reduced to more humble circumstances, and contents himself only with the basic necessities of life. He now lives in Paris with his close friend, the anonymous narrator of the stories.
C. Auguste Dupin the three stories, Dupin travels through three distinct settings. In "The Murders in the Rue Morgue", he travels through city streets; in "The Mystery of Marie Rogêt", he is in the wide outdoors; in "The Purloined Letter", he is in an enclosed private space. Dupin is not actually a professional detective, and his motivations change through his appearances. In "The Murders in the Rue Morgue", he investigates the murders for his personal amusement, and to prove the innocence of a falsely accused man. He refuses a financial reward. However, in "The Purloined Letter", Dupin purposefully pursues a financial reward. While