And even in the stories in which he appears, there is very little to Moriarty. He really is a phantom in the wind and when Holmes tells Watson that he is responsible for pretty much all the crime in London, the reader must surely wonder why he’s never been mentioned before. That wonderful epithet, “the Napoleon of Crime”, doesn’t even belong to him. It was appropriated by Doyle after he heard a police inspector describing another criminal, the very real American thief and smuggler, Adam Worth. Even his name came second-hand when two Irish boys, the Moriarty brothers, arrived at Stonyhurst College, the Catholic school where Doyle himself was a pupil. What then is Moriarty’s secret? Why has he endured when others have faded? And – most pertinently, - if you are in the business of creating literary villains, what might you learn from him? It’s certainly a rule of fiction that all heroes have to have an adversary worthy of them. Harry Potter and Voldemort. Luke Skywalker and Darth Vadar. King Arthur and Mordred. So where exactly do you begin?