Disclaimer: nothing mine, of course. BBC and Conan Doyle share the rights. I claim the faults.
Mary Mor(st)an
She really loves John. Not quite like she loved James though. But then again, no one was quite like James finally s death a suicide. The suicide of a finally-exposed, weak-minded, psychotic fraud.
She doesn't try to steal Sherlock's place in his heart, which is exactly why they can move on together. She knows that Sherlock is the real deal better than most after all, though she can't let it slip if she wants to keep John. She has every intention to do so. She heard James rant enough about Sherly dear. She has been jealous of him so long. She would have known how to make the most out of being the consultant criminal's obsession.
And so John, 'the psycho's victim' in the public eye goes on openly grieving, slowly moving towards acceptance. An acceptance that she'll never reach. She was the girlfriend of 'poor used Richard', and yet she keeps it all inside, permanently stuck in anger. Of course she's angry, no, furious because they (evil ones or not) were supposed to. Bloody. Win! And then Jim had to ruin it all by dying. By his own thrice-goddamned hand. For no conceivable reason. Or perhaps because, after the game ended, nothing was worth staying alive. She wasn't worth staying alive for.
Of course she turned to John. She'd admired him since the pool. No one else in the world could possibly understand her. No one else was going through mad-genius withdrawal. So it's only natural that they hit it off right away. They were really one soul in two bodies, and that soul was breaking further and praying for an impossible miracle.
Later, when Sherlock came back from the dead (bastard!), she's struck almost physically by the unfairness of it all. She hates Sherlock as much as she honestly likes him. He's too much like Jim for her not to be entranced, even while she reprimands herself for it; but, he'll never be Him.
And in some ways, everything that happened is all Sherlocks 'the good doctor', yes. Surely a good man. But being simply good is too little, she's positive, to deserve a miracle. Why was only John awarded his very own Lazarus? Her husband's happiness stings. She shouldn't complain, though. God is merciful and fair. And geniuses are a heartless bunch that will make you mad in the same breath that they make you fall in love with them all over again. So when she finally sees that two- second clip, not screaming is all she can do to keep her secret.
Did you miss me? God, yes. Of course, Jim, you absolute wanker.