Mystrade

Mystrade is the non-canonical relationship between Mycroft Holmes and Greg Lestrade from Sherlock. Mystrade is the second most common slash ship in the fandom and is popular amongst a small, but devoted group of fans.

Mystrade is a rather unusual ship, because in the first season of Sherlock the two characters never appear in a scene together, nor mention each other. So at that point it wasn't even clear if the characters knew each other. Only in the second season did Greg mention Mycroft, so the fans knew for certain that they knew each other. The two characters first appeared in a scene together in the Christmas Special, which aired after the third season. However, in the entire running of the series, the two characters have never exchanged words on screen.

Because of the complete lack of canonical evidence, most Mystrade shippers share common head-canon ideas, meaning things that fans believe to have happened. For example; most fans believe that Mycroft and Greg first met some time before the very first episode of the series and that Mycroft asked Greg to keep an eye on Sherlock and are regularly in contact.