Hercule Poirot sort of obsessive-compulsive" in Poirot. As mentioned in "Curtain" and "The Clocks", he is fond of classical music, particularly Mozart and Bach. In "The Mysterious Affair at Styles", Poirot operates as a fairly conventional, clue-based and logical detective; reflected in his vocabulary by two common phrases: his use of "the little grey cells" and "order and method". Hastings is irritated by the fact that Poirot sometimes conceals important details of his plans, as in "The Big Four". In this novel, Hastings is kept in the dark throughout the climax. This aspect of Poirot is less evident in the later novels,
Hercule Poirot often misleading about his past to gain information, the truthfulness of that statement is unknown; it does however scare off a would be killer of his wife. In the short story "The Chocolate Box" (1923), Poirot reveals to Captain Arthur Hastings an account of what he considers to be his only failure. Poirot admits that he has failed to solve a crime "innumerable" times: I have been called in too late. Very often another, working towards the same goal, has arrived there first. Twice I have been struck down with illness just as I was on the point of success.