In the novel Crooked House, Philip Leonides is the second son of Aristide Leonides. Philip is a historian and spends most of his time writing books on obscure historical topics which nobody buys. His father had given him enough money so that he could afford to do it. Philip moved into Three Gables early on in 1937. He might have resented the fact that his father's favourite was the elder son Roger which he gave his business empire to. This might have been a plausible motive for Philip to murder his father but even his father, in a letter to his lawyer Mr Gaitskill, remarked that Philip is too unsure of himself to do anything except to retreat into his books.
Philip is married to an actress Magda West, and despite the contrast in their personalities, they appear to get on well with each other. They have three children, Sophia, Eustace and Josephine.