The first thing that Sherlock thinks when he meets Mary Morstan, after everything has settled and he's nursing a black eye; after John's tears and anger and finally blessed relief; after disentangling himself from John's embrace; after coming home to find everything a little different, a little unfamiliar; the first thing he thinks when he meets his blogger's fiancée is this:
But she's nothing like me.
Mary Morstan is vivacious in a way that he, Sherlock, is not. Her laugh is rippling, untethered, big. She's messy and silly and loud. She smiles unreservedly. She's alive; something Sherlock has not been for almost three years.
And, as much as he is loathe to admit it, even to himself, she's smart. She's intelligent. Not as intelligent, obviously, as he, but intelligent in a way that he must admit is valuable. She's empathetic in a way that Sherlock cannot fully grasp. She not only understands people's actions, reactions, their emotions, but she knows what to do with them. She knows how to read a person and exactly the steps needed to make them feel comfortable, warm, safe. Happy.
And, admittedly, John does seem that. Happy.
Sherlock would not describe Mary Morstan as manipulative, per se. But she knows how to be liked. She thrives in complex social situations that require keeping tabs on the thoughts, emotions and needs of many people at once. Everyone loves Mary Morstan, and Sherlock, begrudgingly, admires this quality in her.
Not because she's kind, or warm, or altruistic; not because it comes naturally to her, but because she is calculated, meticulous. Sherlock can see the effort it takes. But Mary Morstan isn't malicious. All of her emotional intelligence, her unique skill, her consistently kind yet fluctuating personality – always attuned to the situation, aware of the context – is keenly tuned, precisely aimed at one goal: the happiness of others.
It baffles him.
It is also incredibly useful. Mary Morsten has a practiced ability to put people at ease.
She's nothing like me.
They share some commonalities, of course. A difficult childhood; a formal upbringing; a fascination for puzzles: his scientific, hers emotional; a deep, loyal affection for one Doctor John Watson.
A quiet, unaddressed broken-ness.
Physically, they could not be more dissimilar. Mary Morstan is tiny, barely coming up to John's chin. Sherlock looms over her. She has dark eyes and light, close-cut hair. She has freckles and a small gap in her teeth, a remnant of her sparse resources as a child, alone in a state-funded, oppressively religious boarding school. Her movements are light, familiar. She is generous, wasteful with physical contact. She'll sooner place a small hand on one's shoulder than call one's name.
Somehow, her touch never seems intrusive. It merely acts as punctuation, clarification.
Nothing like me.
In the weeks following his return, Sherlock must adjust to this new presence in his life. John is on edge, of course. He's a mess of many things, but his predominant feeling seems to be one of relief. Sherlock's arrival, after all this time, seems to have let all the tension out. Or perhaps that is Mary's doing. For her part, Mary Morstan adjusts to Sherlock's sudden appearance, his constant intrusions, his moods and his whims, his obtrusive presence, incredibly well.
An example: one evening, a few weeks after his return, Sherlock picks up his violin, tunes it, and begins to play. Mary Morstan, far from disrupted, hums along. John continues to read the paper, but Sherlock (and likely, Mary as well) does not miss the small upturn of the corners of his mouth.
It's obvious to Sherlock that John is very much in love with Mary Morstan. She makes him laugh. She challenges him. She teases him. She jostles him out of bad moods and she pushes him out of his comfort zone. She wraps her small arms around him and he breathes her in. Mary Morstan, Sherlock thinks, in a spate of rather uncharacteristic poeticism, is a rush of blood to the cheeks made human. She is warmth and coyness and humour.
And, he deduces immediately, Mary Morstan loves John. She is endlessly amused by his curmudgeonly ways, fascinated by his often dull stories, impressed by his intellect, aroused by his quiet strength and rather average physicality. He often catches her gazing at John, content. Mary Morstan, Sherlock can tell, is captivated by John. She is drawn to him, entangled with him, pulled, happily, under his spell.
Like me.