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.
Mary Russell (character) as well as meeting Holmes, Russell prepares for and eventually passes the entrance exams to Oxford University, where she reads chemistry and theology. In addition to Holmes, who acts a mentor and father substitute early in their relationship and eventually becomes her husband, Russell becomes close to other characters from the Holmes canon: she considers Mrs. Hudson, who has accompanied Holmes to Sussex as his housekeeper, to be a mother figure, and she refers to Dr. Watson as "Uncle John" and Mycroft Holmes as "Brother Mycroft." She is also close to her farm manager Patrick and tends to make friends