8. Moriarty Won't Overstay His Welcome
As previously mentioned, Moriarty's reputation far out weighs his number of appearances: He is often viewed as Holmes' greatest enemy, even by those who are not fans, yet he is only in two stories. It is very rare for this to happen to an arch nemesis, as writers often concede to popular demand for their swift return. Whilst this works for some villains, the Joker is a particularly apt example, there are others who suffer from over exposure. One of the worst cases that springs to mind is that of Norman Bates; a character with three sequels and a new prequel series. Part of the brilliance of the original Psycho is that Bates' motivations are only revealed towards the end. The final shot of the film leaves the viewer pondering the mental state of the serial killer and what the future holds for him. This ambiguity was a key component of the film, and there was no need to demystify an intriguing character through unwanted sequels. Moriarty has already had more appearances in the series than the novels, but has not outstay his welcome. Ensuring the character does not return will leave him as intriguing as he has always been.