She doesn't ask him.
Not when he first meets her, a smiling face in the middle of questioning glances and frowns when he is introduced at his new job – a hospital as far away from Baker Street and St. Barts as he can manage without leaving London – nor when she brings him his first cup of coffee at the start of his first day. She just hands him the warm steaming cup with an equally warm smile, saying he looked like he could use it.
She wishes him good luck and disappears again before he can thank her.
It's true, he looks like the dead. He knows it, but he doesn't care. Who can blame him for being too afraid to close his eyes at night? Not when all he can see are those blank blue eyes staring up into nothing and his last words echoing in his ears.
But she is right. He could use it. So he takes the coffee, ten minutes before they start their shifts and it continues from there. Every day, ten minutes before his shift, she brings him a cup of coffee and he finds himself looking forward to the days they work together.
She's a nurse, a good one, with a caring heart, a sweet voice and a good instinct when it regards her patients. He finds himself smiling naturally when they find time to talk.
But she still hasn't asked him.
So he remains apprehensive.
She still hasn't asked him when he finds the courage – and the emotional stability – to ask her out. She agrees with a smile that manages to brighten the constant darkness surrounding him. His other co-workers ignore him mostly, the contact a bare minimum of 'hello's' and 'goodbye's' and patients charts, which suits him fine. But she manages to find a way through the cracks of his armor he put up since the Fall and he finds that he's okay with that too.
He takes her to a small restaurant – he can almost hear his voice accusing him of being dull and predictable, but he doesn't care – and he spends the night picking on his food, waiting for the inevitable. But the question doesn't come.
She talks about her family – parents dead, a sister who she's close to – the reason she became a nurse and she asks him about his military career and Afghanistan and he finds himself talking without restraint and he relaxes more as the evening progresses.
When he's home, a small flat close to his job, far later in the evening he expected, he realizes she still hasn't asked him. He decides to take the risk and calls her the next day for a second date.
They have been seeing each other for several months and the darkness seems to have lifted somewhat. He smiles more often, he sleeps better – especially when he is sleeping next to her at her place – and he finds it in his heart again to talk to mrs. Hudson. She smiles at him, compliments him on moving on and when he introduces them to each other and the two women immediately take a liking to one another. But they don't mention him, nor the Fall and he is grateful. He isn't ready. Not yet.
It happens when he already lives with her. Her flat is large enough for the two of them, she said, and he spend nearly all of his free time at her place anyway, might as well move in.
He stands in front of the mirror, their mirror – God Sherlock, she might be the one! – when he finds himself thinking of him, thinks of his name, even says it out loud to himself and it doesn't hurt as much anymore. He feels a weight lift of his shoulders when he can't remember the last time he saw the blue dead eyes in his sleep and he comes to the conclusion that his nightmares have almost disappeared since moving in.
He takes a deep breath and confronts her during dinner.
'Why haven't you asked me?'
She looks up, surprised, before she catches on without him having to elaborate. She is clever, Sherlock. You would have at least tolerated her. 'I didn't think it was my place to ask.'
'Nobody else seemed to think that way.'
She shrugged and continued with her dinner. 'Besides…you didn't seem like you wanted to talk about it.'
He nods and takes a large sip of his wine. Liquid courage. 'I think I am now.'
She stops eating and looks at him with concern. 'Are you sure, John? I don't…'
'Mary…'
She holds her tongue while he talks. About how bleak his life was after Afghanistan but before Sherlock, how he met him, the cases, the madness, the thrill of it all. About Moriarty and his game, how he staged everything, how he managed to make Sherlock look like a fake – I won't believe what you told me, Sherlock – the phone call – his note he had said – and the Fall. Mary sits and listens. She doesn't interrupt him and when he's done he finds himself shaking with relief and grief. She rises from her seat and just holds him through his breakdown.
She comes with him to the gravesite the next day, two years exactly after the Fall and holds him hands when he says his goodbye's, for real this time.
He has to move on and with this beautiful nurse, woman, friend, lover, his Mary Morstan, he might just be able to.