(Or: How The Watson’s Marriage Was Done So Right, It Hurts - A Johnlock Perspective)
When Mary was first introduced into the show, we very graciously welcomed her into our hearts, trusting that the writers had some kind of plan. We knew that they were facing the difficult task of staying true to canon while further developing the relationship arc between John and Sherlock. Not an easy feat, but we had faith: Eventually, we would see Mary’s true colours, John would return to Baker Street - all would be well.
But, alas, it did not happen. And the fandom was flabbergasted. What were Mofftiss playing at? However, there are actually two really good reasons for doing what they did:
One, you can’t just turn one of the very few original female characters into something negative. I mean you can, but I really don’t think Mofftiss wanted to. Two, there was a much, much more beautiful route. And Mofftiss took it.
Because what do you do, when you can’t make a character lovable due to the risk of heteronormativity, and you can’t make her unlovable due to risk of misogyny? The answer is: You make her awesome. You make her the best, most brilliant hero ever. And then you let her make a really strong case in point: No one can compete with Sherlock Holmes.