Mycroft Holmes

Mycroft Holmes is Sherlock's older brother by seven years. They have a very strained, oppositional relationship and Mycroft even refers to himself as Sherlock's "arch enemy." He frequently has his people grab John Watson off the street and deliver him so that Watson can relay messages from Mycroft to Sherlock.

He claims to occupy a "minor position" in the government, but his access to high level classified information and locations, and ability to manipulate computer systems, would imply otherwise. Sherlock says Mycroft occasionally "is" the British government, when he's not doing freelance work for the CIA.

Despite the supposed distance between the two, Mycroft also tries to look out for Sherlock from afar, sometimes warning Watson when Sherlock is in danger.

The brothers share the same air of imperiousness and arrogance and Mycroft seems to be as intelligent as Sherlock, but has chosen to use his smarts for intelligence work

Background: Was one of the founders and is a member of the Diogenes Club, a men's club where members are not allowed to speak for reasons of peace and quiet.