Molly wondered why he kept coming back. Every time Sherlock Holmes, the world's only consulting detective, swept in through the doors of the morgue like he owned the place, he would find some way to belittle and insult the work that she put so much effort into, managed to blow it all off with a casual flick of his fingers and a stream of scathing deductions. It didn't make any sense. If she was so useless, if she was so incompetent, then why would he continuously come back to her? There were other pathologists working in St. Barts, and there were plenty other morgues in London that he could go to if he wanted. Yet, ever so consistently, he came back to her, the insignificant Molly Hooper. He refused to even be in the same room as the other pathologists, and he sneered at any other morgue as if it was something scraped off the bottom of a shoe.
"Why do you come back?" she asked, murmuring the words to herself.
The dark head of hair bent over a microscope came up. "Pardon?" Sherlock asked, turning his intense, pale gaze towards her.
Heat flooded her face and neck; she hadn't really meant to say it aloud. His unblinking eyes were still focused on her, waiting for an answer, so she repeated, "Why do you come back?"
It was almost imperceptible, but she was too used to his presence to miss it. The line of his shoulders went stiff, a degree of tension coming to his back. "Because I am selfish," he replied at last.
Molly frowned slightly. Selfish? Well, bloody hell, she already knew that one. She also knew that he was stubborn and brilliant and insufferable and the biggest git that she'd ever met in her entire life. What else was new? She opened her mouth to ask, but too late. He'd already returned to whatever slides he had underneath the microscope, and she knew that once he put his blinders on, there was nothing she could do to make him budge. He became oblivious to the world.
Still, she persisted. Sometimes it'd be a few days before she'd ask again, sometimes it'd be a month or two. But still, she'd ask. The same question, five words, "Why do you come back?"
And every time, without hesitation, he'd give her the same answer: "Because I am selfish." No matter how she prodded or probed, he would never give more of answer than that. "Because I am selfish."
And then came the Fall. He came to her, for some inexplicable reason. Why would he come to her—mousy, timid little Molly who spent more time with the dead than the living—when he had someone like John to look out for him? She didn't count, didn't amount to anything much in the long run. Yet he came to her for help, coming as close to begging as Sherlock could come, for her assistance, for her trust. And she'd given it to him. She'd helped him convince the world that he was dead.
Three months after his faked suicide, which she had helped perpetuate, she had come home from the morgue to find him waiting, sitting outside her door, bruised and bleeding and beaten all to hell. Molly helped him inside—how did someone so thin weigh so much?—and tended to the rainbow of bruises that coloured his flesh in terrible shades of brown, bluish-purplish, angry red, and sickly yellow-green. She disinfected the collection of wounds, taped up what looked like a cracked rib or two, and coaxed him into eating proper food. As she knelt beside the couch where he lay curled up beneath her quilt, she paused slightly, one hand resting on his arm. "Why do you come back?" she asked once more.
"Because I am selfish," he replied in a drowsy murmur. And he placed his slim-yet-strong hand over her own, curling long fingers around her wrist.
She realised it then. The knowledge that had been slowly building up in her washed over her all at once, like a great tidal wave. Molly closed her eyes tightly as she struggled to keep herself together.
He said he came back because he was selfish.
He came back because he loved her.
Sherlock wondered why she stayed. Most people could not bear to be around him for five minutes, yet Molly put up with him day after day, week after week. She was like steel, it seemed. She could bend and twist and reshape herself, yet she was almost impossible to break. She was a kind of steel that even he couldn't break. Perhaps that was how it started.
He had never been in love before. He felt some sort of lust when it came to The Woman, but that was more mental excitement than physical. He was more intrigued with her mind than her body. But love, actual love, was something he was not familiar with. There was no way to quantify it, no way to explain it. It simply was. It'd snuck up on him too, a thing practically unheard of. It began small. Love did not simply spring up out of nowhere, despite the horrifying number of sickeningly overly-romantasized filmes and novels that claimed otherwise. First, he realised, came the sensation of 'like'.
He liked Molly's quiet acceptance of his presence in the morgue, liked how she worked around him, always soft-spoken and quiet as to not disturb his work. He liked how she never called him a machine or inhuman or a freak because of his deductions. He liked the way she'd slip him body parts in sealed containers for him to continue his experiments at home. He could sometimes go for hours, even days on end without speaking, yet so could she. There were times that he would spend hours in the morgue with her, and neither of them would ever say a word to each other. And he liked it. He'd eventually come to need it, that kind of peaceful silence that went without questions or suspicion. There were days that he craved the tranquil quiet of the morgue with her unassuming presence working alongside his. And slowly yet surely, with all the steadiness of chain reaction approaching critical mass, all those little 'likes' eventually turned to 'love'. He had, unexpectedly and unbelievably, come to love his little pathologist.
He knew, though, that she couldn't possibly feel the same way. Perhaps she felt some kind of misguided infatuation, but no-one could ever truly love Sherlock Holmes. It was an impossibility. He was unable to be loved. So when she asked him, "Why do you come back?" his first impulse was to reply that he doubted he would be able to function without the soothing reprieve that she offered. Instead, he answered, "Because I am selfish," because that was the truth. He was selfish. He was selfish for always craving the presence of Molly, the woman that counted, for wanting to experience her quiet, unassuming strength and keep that inner steel to himself. And whenever she asked, he always gave the same answer.
After the Fall, when the world believed him dead and even his blogger, the only best friend he'd ever had, mourned him, Sherlock returned to her because he knew she would be there for him. No matter what state he showed up in, she'd open the door and tend to the array of hurts he'd collected without question, without demanding anything of him in return. The very thing he loved most about her.
Even after his return to the world of the living, after John's passionate fury, Molly had gone unchanged. Steel as ever, she had bent without breaking. And after all the years of knowing her, Sherlock still wondered why she stayed. Why she hadn't cast him out on his ear by now. Why she was still...Molly.
"Why do you stay?" he asked, lifting his gaze from the samples laid out before him.
Molly turned towards him. Her cinnamon-chestnut hair was braided back, draped over one shoulder, and he felt an impulse to undo the plait and run his fingers through it, as he always did. A tiny smile came to her lips—which were definitely not too small—and a soft, warm look came to her eyes. It was the kind of look that Sherlock had always wanted from her, and it made an unfamiliar sensation of warmth coil in the pit of his stomach.
"Because I am selfish, too," she replied softly.