Disclaimer: The characters of Sherlock are not mine, nor is the story, nor are the characters from the original stories by Sir Arthur Conan Doyle. I make no monetary profit from this.

Note: Written for the following prompt on the Sherlock kink meme:

Nothing she does is good enough, and not just for Sherlock, for anyone. Her parents, her teachers, her bosses, her boyfriends, Molly has lived her entire life in criticism stew.

One day it's all too much and she snaps. How badly she snaps - from yelling at someone before bursting into tears to unleashing the zombie hordes upon the world - is entirely up to the filler.

I freely admit that zombies are a guilty pleasure of mine, and warn you of (extremely minor, only-exists-on-the-blogs-and-has-four-legs-and-presumably-a-tail character) death. And I would like to take this opportunity to point out that I meant to write crack.

The Effects of Excessive Pressure on Molly Hooper, 31, Single, Lab Rat

There is such a thing as too much pressure. Beneath the earth, extraordinary, almost unimaginable amounts of pressure and heat act on huge, perfectly innocent masses of rock, pushing their molecules into different positions, fixing them into strange lattices, changing them into something new and possibly even beautiful. Metamorphic rock.

Molly has never been allowed to think of herself as metamorphic rock, or even something that could eventually become metamorphic rock. She has mostly been made to think of herself as mud.

Nasty mud. The kind with organic bits floating around in it that gets trodden on anyway because it is in a very unfortunate place on the sidewalk.

She is the youngest of four children, and her parents have been constantly telling her, since childhood, that she is either not as good as her elder sister and brothers, or, if she actually manages to accomplish something, that somebody else managed to do it before she did so her having done it doesn't count. Her siblings reinforce this view of things. It used to make her cry.

Molly doesn't talk much. In school, she was brilliant, but very quietly so, the kind of brilliant that gets overlooked by teachers (who take it as a matter of fact, and are thus more likely to remark on a lapse of it, rather than its presence) and used by classmates to get homework done under the guise of proferred friendship. This carries over to her work so that, somehow, she is always passed over for promotion, even if she does more work - and, she knows, better work - than anyone else. It used to frustrate her, and she used to go home and punch her pillow - quietly! - until the feeling went away.

She hasn't had much luck with boyfriends. She spent all her years at uni hopelessly crushing on one boy (she hadn't done anything about it because he'd had a girlfriend when she met him, and she only found out that he'd actually been single for quite a long while when she learned he had a new girlfriend a couple of years later). He'd been nice to her, though, if a little condescending. That, at least, was better than the boy who had asked her if she'd like to be his girlfriend and then changed his mind a week later. And then there was Sherlock Holmes.

Molly is smitten by Sherlock Holmes. It's unhealthy and she tries to get over it (she's not as daft as people think she is) but she ends up doing everything she reasonably can for him anyway. She hopes that maybe he'll be different, or that maybe he'll change, or maybe he'll agree to go out for coffee and they can be friends at least because they do have a lot in common, even if it isn't obvious. She ends up getting a cat to keep her company, because at night her flat is desperately quiet, and any excuse to not answer her mother's phone calls is welcome ('Sorry, Mum, I was chasing the cat').

She names the cat Toby in direct defiance of her feelings (and he's the wrong color too), and writes about it in her blog, which nobody reads anyway.

Jim had liked Toby. And he had liked Molly too, more than the cat. And he had liked Glee, which, until then, Molly had watched with the volume down so as not to disturb the neighbors. He had also apparently liked covering people in Semtex and blowing them up if Sherlock didn't get his puzzles right. Molly is stunned and hurt when she learns this. It is suddenly likely that Jim felt more real affection for the cat.

No-one tells her that she should have known, should have been able to tell. Somehow, that is worse, because it means that people expect her to be gullible, a pitifully easy dupe who can't even remember how to turn on the spell-check. She can't bear to look at Sherlock anymore, because she doesn't want to see the contempt that she imagines will be in his eyes. His opinion of her was already only thinly veiled before what happened at the pool.

She suspects that Sherlock is gay. It's the way he looks at that doctor friend of his. At least she has the cat.

And then some stupid idiot runs over Toby.

There is such a thing as too much pressure. Eventually, somewhere, something will snap.

It happens so fast - she doesn't even know why Toby suddenly decided to leap out of her front door and into the street when she got home that night - that Molly fails to get the car's plate number, or its make and model. The driver didn't stop, didn't apologize, didn't even acknowledge what he did with the slightest change in speed.

Molly has seen the movie where Johnny Depp kills people and Helena Bonham Carter makes them into pies (she likes musicals, which was why she watched, though with a subtitle like ''The Demon Barber of Fleet Street' she ought to have seen what was coming). She feels like that now.

Molly won't make pies though, because she knows what people look like when they're dead, and it's positively unhygienic. She's a smart girl, though, in spite of what everyone else thinks. She has a better idea.

Sometimes there is an advantage to working in a morgue.

Sometimes the advantage doesn't even have anything to do with briefly getting Sherlock's attention.

Molly uses the unclaimed bodies, the John Does (yes, the Johns, because the idea of working on the women makes her uncomfortable, and there is a certain vindictive pleasure she gets from experimenting on things named John - no, she isn't quite over Sherlock yet). She is patient and painstaking. She does her research, talks to experts, pays for her transactions in cash.

She ponders her motives while she works. It's not that she's angry. She gave up on being angry long ago. She just can't believe that she lives in a world where someone can run over a perfectly innocent cat and not even feel sorry for it. She can't believe that people are allowed be so cruel. She can't believe that people like that are allowed to live.

She just doesn't want to put up with it anymore.

Besides, it's not like she's going to kill anybody, not like Jim. If anything, she's giving the bodies she's working on a second chance at life. Sort of. At any rate, if there's going to be any killing, it'll be them that're going to do it.

The first one just sort of spasms limply on the table. It doesn't discourage her. She didn't expect to get it right on her first go.

The second one manages to lurch a few steps forwards before collapsing in a very messy heap. She wipes the floor with 70 percent ethanol and bleach afterwards to disinfect it.

The one after that is her first legitimate success. Molly wishes it would go a little faster, but she's working on that.

The next one was completely unintentional. Robin from upstairs became number four when he got bitten as he chanced upon what Molly had hidden in the broom cupboard. He had been searching for a mop to clean up some spilled phosphate buffer. Molly wanted to apologize - he was nice, as far as she knew, even if she didn't quite trust nice anymore - but she can't be properly sorry once she sees how fast Robin can go. She thinks it has something to do with the nervous system still being in good working order.

It is only a very small matter of time now. She plans to set the first few on Jim, just because she can. And then she'll let them do whatever they want.

Molly does not care. No. She doesn't give a damn.

Sherlock notices the dark circles under her eyes, and he comments on how she seems to be drinking more coffee. She hands him his own coffee wordlessly, wondering how he'd react to a zombie apocalypse. One precipitated by Molly Hooper.

She still likes him, though, and will probably tell him that they can be taken care of by a quick shot to the head.