Mycroft is one of two major characters being added to this popular franchise. The other being the as-yet-uncast Moriarty. Mycroft is Sherlock Holmes' (Robert Downey Jr.) older, smarter brother. His sleuthing powers far exceed those of his younger sibling, yet he is incapable of performing any sort of detective work due to his sloth-like nature and indifference to crime. He is simple unwilling to put forth the physical effort needed to bring cases to their conclusion. He would rather be considered wrong than take the time and prove himself right.
A Moriarty casting announcement is expected soon, as Guy Ritchie is gearing up to shoot this sequel before the end of the year. Production will once again take place in the UK, with Joel Silver and Susan Downey producing.
Sherlock Holmes: A Game of Shadows was released December 16th, 2011 and stars Robert Downey Jr., Jude Law, Noomi Rapace, Rachel McAdams, Jared Harris, Stephen Fry, Paul Anderson, Kelly Reilly. The film is directed by Guy Ritchie.