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 pastiches also makes a minor but significant appearance in Warren Ellis and John Cassaday's comic book series "Planetary". Michael P. Hodel and Sean M. Wright presented a mystery-adventure "Enter the Lion: A Posthumous Memoir of Mycroft Holmes" (1979) in which Sherlock's older brother prevents a conspiracy involving a return of the American "colonies" to Great Britain. Sherlock makes appearances with Victor Trevor (from The Adventure of the Gloria Scott), Professor Moriarty and Moriarty's father. Carole Nelson Douglas has written a spin-off series centring upon Holmes' nemesis Irene Adler. The first book is titled "Good Night, Mr. Holmes" and takes place concurrently