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 and English, Poirot is also fluent in German. Gustave[...] was not a policeman. I have dealt with policemen all my life and I "know". He could pass as a detective to an outsider but not to a man who was a policeman himself. Hercule Poirot was active in the Brussels police force by 1893. Very little mention is made about this part of his life, but in "The Nemean Lion" (1939) Poirot refers to a Belgian case of his in which "a wealthy soap manufacturer[...] poisoned his wife in order to be free to marry his secretary". As Poirot was