He's not really sure how it happens – he's dizzy with pain, John's scream still echoing in his ears – but her arms are so warm and gentle around him that for once he just stops thinking.
She doesn't cry as he leaves in the morning, and he's grateful to her for that.
Two years later nothing is the same anymore; Mrs. Hudson tells him that John is about to get married, and Molly has had a child with some bloke.
He supposes his friends deserve happiness, all he has to do is let them go. John yells at him for lying about his supposed death, but in the end asks him to be his best man and he simply can't refuse.
It's at the wedding that he finally sees Molly. Her child is beautiful, he looks like her except for his eyes – and that's when everything falls into place at last.
"You could have told me," he murmurs, and she almost chokes on her glass of wine.
"It's not – we're fine, Sherlock. Really. You don't need to worry about us."
He's vaguely aware of something shattering inside his chest, but he manages to master his emotions as he always does. "Okay," he says, then walks away.
A week later John is on his honeymoon, Molly is probably taking a walk into the park with her little boy, and Mrs. Hudson is trying her best to get him out of his bed.
"You're not ill, are you Sherlock?" she asks again, and he only shakes his head.
He's fine, everything is fine. Alone is what protects him, that's what he told John two years ago; if only he could stop breathing as well, everything would be better still.
Another week passes by; Lestrade shows up asking for his help with a case, but he's pretty sure it's Mrs. Hudson who begged him to do so. He points out who the killer is in less than thirty seconds, then turns to face the wall and shuts his eyes again.
John texts him a couple of times, but then he's on his honeymoon and Mrs. Hudson wouldn't dare to share her worries with him now. He's not really expecting her to turn to Molly, and yet he should have known; Mrs. Hudson is so fond of him she would do anything to make him feel better.
"What's wrong?" she asks nervously, fidgeting with the hem of her shirt.
"Nothing's wrong. Why are you people always asking?"
He's not going to admit he has a heart – not now, nor ever. It wouldn't be like him, all rationality and mind skills; Sherlock Holmes can't afford having a heart, so it might as well shatter into a thousand pieces.
"Is it about the child?" Molly tries again, and once more he's surprised at how perceptive she can be at times. "I thought you didn't care."
"I don't," he says stubbornly, though he knows she can tell he's lying through his teeth.
"He's downstairs with Mrs. Hudson. Do you want me – I mean – would you like to see him?"
The lump in his throat is so huge he can't swallow it down, no matter how hard he tries.
"No, I'm fine. I guess you're right, it's better this way."
"Sherlock."
He pulls the sheet over his head, so that she can't see the tears in his eyes. Soon he's shaking with sobs, he feels so lonely he thinks he might die for the sheer pain of it.
But it doesn't matter, doesn't matter at all.
Sentiments are dangerous, and that's the penalty he has to pay for ever indulging in them. He's been an idiot, he should have known better than that.
In a way he's relieved when he hears the door close behind her. Molly has to go on with her life, and he'll eventually learn to live with it; he's not boyfriend nor father material, that's the hard cold truth – and it won't ever change.
His heart skips a beat when he feels a minute hand pulling at the sheets, a pair of piercing blue eyes staring at him with sudden interest.
He tries to avoid Molly's eyes as he runs a finger through the child's soft hair.
His son smiles knowingly, as if he's already deduced who he actually is.