Baker Street Wiki
Baker Street Wiki

Mycroft Holmes is the older brother of Sherlock Holmes.

When Sherlock is called to London to revisit an old case, he is forced to face his older brother. Although the siblings suffered a drastic falling-out a few years earlier, Mycroft allows Sherlock and Joan Watson to stay in his home, 221B Baker Street. It is learned that the source of the two brothers' estrangement occurred when Sherlock deduced that Mycroft's fiancée did not love him, and proved he was correct by having sex with her (seven times, including a time in a pod on the London Eye), which ended the engagement.

Sherlock's reunion with his brother happens by accident when he returns home to Baker Street, only to discover that his father has gifted the home to his brother, Mycroft. Sherlock believes that Mycroft is a lazy, unaccomplished man. While Mycroft gives as good as he gets, he is also trying to mend fences with his brother after having had Graft versus Host disease, following a bone marrow transplant to treat advanced leukemia.[1]

He and Joan Watson are quite taken with each other, and Sherlock later deduces that they have had sex.

Shortly afterward, Mycroft arrives in New York and enlists Holmes and Watson to help solve a case involving his former fiancée.[2][3] It is also revealed in this episode that Mycroft's restaurants are all named Diogenes.

Mycroft shakes Joan and Sherlock's trust in him when he risks Joan Watson's life as part of an MI6 operation.[4] He leaves the country and can no longer contact Sherlock and Joan.

Years later, Sherlock finally addresses his residual anger at his brother, and decides to reach out to him once more. However, his contact informs Sherlock that Mycroft died some ten months earlier in New Zealand of an intracranial haemorrhage apparently brought on by some aspect of his leukaemia or its treatment. When Watson points out that the elder Holmes has faked his death before, Sherlock seems adamant that this is genuine.[5]


  • The "Diogenes" name comes from the Diogenes Club in the original stories, where the canonical Mycroft Holmes spends his days. It is described as a gathering place for "the most unclubbable men in London".