Spoiler warning: This article contains information from an upcoming or recently aired episode.

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 new home, 221B Baker Street. It is learned that the source of the two brothers' estrangement was an incident that resulted form Sherlock deducing that Mycroft's fiancée did not love him, and Sherlock needing to prove he was correct. He did this 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.

Shortly afterward, Mycroft arrives in New York and enlists Holmes and Watson to help solve a case involving his former fiancée. ("The Marchioness")[1] It is also revealed in this episode that Mycroft's restaurants are all named Diogenes.

In "Nobody Lives Forever", 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.



  • The "Diogenes" name refers to Mycroft Holmes' club in the original stories, a gathering place for "the most unclubbable men in London".
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