The Adventure of the Greek Interpreter Sherlock Holmes, far from being a one-off in terms of his powers of observation and deductive reasoning, in fact has an elder brother whose skills, or so Holmes claims, outstrip even his own. As a consequence of this, Watson becomes acquainted with the Diogenes Club and his friend's brother, Mycroft. Mycroft, as Watson learns, does not have the energy of his younger brother and as a consequence is incapable of using his great skills for detective work: In spite of his inertia, the elder Holmes has often delivered the correct answer to a problem that Sherlock has brought to him.
Sherlock Holmes housekeeper Mrs. Hudson is the protagonist. Mycroft Holmes has been the subject of several efforts: "Enter the Lion" by Michael P. Hodel and Sean M. Wright (1979), a four-book series by Quinn Fawcett, and 2015's "Mycroft", by former NBA star Kareem Abdul-Jabbar. John Gardner, Michael Kurland, and Kim Newman, amongst many others, have all written tales in which Holmes's nemesis Professor Moriarty is the main character. Anthologies edited by Michael Kurland and George Mann are entirely devoted to stories told from the perspective of characters other than Holmes and Watson. Laurie R. King recreated Holmes in her Mary Russell series