'Sherlock' Season 3: Holmes brothers' rivalry comes from Mark Gatiss
It turns out the man behind Mycroft is based a lot of the Holmes brothers' dynamics on his relationship with his own older brother, Phillip. Older by three years, Phillip often bullied his younger brother and both boys disliked the other. "We only stopped hating each other recently," Gatiss told The Guardian back in 2010. "We never had anything in common. He was painfully shy and found his expression in lashing out at people."
Fortunately, the brothers' relationship -- much like that of Sherlock ( Benedict Cumberbatch) and Mycroft in Season 3 -- has mellowed out in recent years. Daily Mail says Gatiss' upcoming role as Tycho Nestoris in "Game of Thrones," for example, has given the Gatiss brothers a shared interest, since Phillip is a fan of the program.
In addition to playing Mycroft and writing "Sherlock," Gatiss is an executive producer and writer for "Doctor Who," who also wrote "An Adventure in Space and Time," a drama about the beginnings of the show on the BBC.
"Sherlock" will return for Season 4 at some point in the future, hopefully before 2016.