The Adventure of Sherlock Holmes' Smarter Brother Sacker, shares a similar name with that originally applied to John Watson, Ormond Sacker. The film's title and premise are a joke referring to the character of Mycroft Holmes, Sherlock Holmes' "older" brother, who was by both of their estimates a good deal smarter than Sherlock. He was, however, too lazy to become a detective, and did indispensable work for the British government. Mycroft was described by Sherlock in conversation with Watson: Mycroft is mentioned briefly in the beginning of the film, which presupposes that Holmes was one of three brothers. Sigerson's name refers to an alias used by Sherlock
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