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.
Minor Sherlock Holmes characters actually a coded message that invited Sherlock to Eurus's room, allowing Sherlock to save his friend by making a genuinely emotional appeal to Eurus, giving her the love of an older brother and a form of relationship he'd denied her as a child, which convinces her to stand down. She is returned to incarceration, with Mycroft describing her as reduced to a catatonic state, although she responds in duet when Sherlock plays the violin near her cell. Mary Russell is a fictional character in a book series by Laurie R. King, focusing on the adventures of Russell and her mentor