Sherlock: 10 Most Outrageous Fan Theories

9. Janine Is Moriarty's Sister

Janine was Sherlock's temporary girlfriend in His Last Vow, who he heartlessly dated - and even got engaged to - to get close to her boss, the evil media mogul Charles Augustus Magnussen. But is her boss actually another Sherlock big bad and did she have her own agenda in her relationship with Sherlock? Some fans seem to think so...

The word is that Janine is actually the sister of the recently-resurrected Moriarty. Assuming he really is still alive but wanted to wait in the shadows for a little longer, the theory goes that he set his sister up as Magnussen's PA and purposely maneuvered Sherlock to kill Magnussen so that he could take over his huge business, to relaunch himself in the world. And perhaps he encouraged Janine to date Sherlock to mess with his enemy's heart, as he promised to do back in series one.

Of course, the only evidence in the show that these characters are related is that they are both Irish!