|“||Sweetened milk always puts you in a good mood, doesn't it? My little Shirley...||”|
Mycroft is the oldest child of Siger and Violet Holmes and Sherlock's older brother by seven years. He and his brother are highly intelligent compared to their parents who are considered normal, which is surprising to those who know the Holmes brothers.
He and Sherlock helped catch the killer who murdered Mikah's parents. Since Mikah had no other relatives, he and Sherlock would his family from then on.
Mycroft has brown hair and brown eyes and wears a well-tailored suit. He works for British Government, but he's described that he is the British Government. Like his original counterpart, he's intelligent and observant (if not more so) than his younger brother but unwillingly to physically put effort in his intelligence.
He's often aloof and cool, but his most noticeable trait is that he's very manipulative toward Sherlock. He likes to sadistically tease Sherlock by relating embarrassing stories about him from their childhood, and often treat him as a child; an example was when he brought items to help Sherlock escape from prison, he hid them in childish items such as a rubber ducky, a body pillow, and a children's fairy tale book. However, despite his sadistic nature, he truly cares about his brother (though he will openly never admit it) and always asks for Sherlock's help whenever there's a national crisis.
As a child, he described himself equal to adults but played the role of the "perfect and obedient child" for that's what the adults wanted. He's stated that he enjoyed scaring Sherlock for he loved to see him crying to him, but he disliked it when others made him cry for that was his right.
Mycroft has an immense sweet-tooth for he'll often put five to seven sugar cubes in his coffee or tea, and can eat 23 eccles cakes at one setting. He easily gains weight because of this and can be a bit self-conscious when brought up, so he does try to diet whenever he feels that he's gained weight. He also considers himself a food connoisseur and loves to eat gourmet food as well as cook it, but as Sherlock and John have stated, he is a terrible cook. He's a lightweight when he drinks alcohol, so he doesn't drink it and often avoids it whenever he has to attend parties.
He's very attractive like his brother and many women are drawn to him because of that and his high-paying job. However, unlike his brother, he has had girlfriends and knowledgeable about romance, but he doesn't put much effort into the relationship, which causes his partner to walk out on him. He's intrigued of Jane Marple when he learns that she has captured Sherlock's interest so he researches her and watches her plays, and becomes attracted to her as well.
- Mycroft's route was released on March 21, 2017.
- He is significantly younger and thinner than the original version.
- Mycroft's route was the second to introduce Jane's parents, but the first to have his parents introduced.
- So far, Mycroft is the only character to have married Jane Marple in his main route.