Author's note: While this story is mostly fluffy humor, it does contain: vulgar language, nonexplicit sexual content, and the brief and nongraphic mention of the death of a child. Please do not proceed if any of these will offend or injure.

Although he prided himself on his quickness and mental acuity, it took Sherlock an embarrassingly long time to realize that Toby bore more than a passing resemblance to the late, unlamented, James Moriarty.

Small.

Well-groomed.

Cute enough that one did not immediately notice that he was in fact a venomous monster.

And last-but-not-least, murderously obsessed with one Sherlock Holmes.

It wasn't the time the bloody animal had all four sets of claws and his teeth buried in the flesh of Sherlock's arm while Molly swatted ineffectually at him and said, "Toby, no! No! BAD BOY TOBY!" On that occasion, he acknowledged that he had perhaps been too rough while petting Toby's belly. Certainly regrettable outbursts were something that Sherlock had inflicted upon others, so it seemed unjust to criticize the cat. Even when he had to get John to prescribe him antibiotics for the bad one under the thumb.

Nor was it the time that the cat urinated on his clothes while he was using Molly's shower. Sherlock had a better than passing knowledge of feline psychology, and suspected that this was an instinctual response to the profound and unfamiliar smells clinging to his "homeless junkie" costume. Frankly the cat urine had improved the disguise.

No, he didn't realize that he had incurred a vendetta until the first time he and Molly used her bed for something other than sleeping. It wasn't their first time together, happily, but it was only their third (would have been their fourth if Mrs. Hudson hadn't come up to do the hoovering). They were... engaged in intimate contact... when Sherlock felt a furry weight on his toes.

Manfully, he ignored this and pressed on.

He could not ignore the mournful banshee wail that the animal started up with two seconds later. Nor could Molly, who raised herself onto her elbows and peeped over his shoulder and cooed, "Ohhhh, poor Toby. We must have scared him."

The cat yowled again, and Sherlock could swear the animal looked smug.

"Molly," Sherlock pointed out, "I've seen your cat trying to mug a perfectly inoffensive Alsatian. I really doubt he's frightened of this."

Without him realizing exactly how, the intercourse was abruptly not happening any longer and she was picking up the wretched cat and holding him in her arms like a baby. A fifteen pound, fanged baby. Which definitely was looking smug.

"Who's my poor ickle brave watch kitty? You are!" she said, before completely altering her tone, "They have protective instincts too. Think of it from his point of view... it probably looks like we're fighting."

"Does he always do this?"

"Well, no, not really. He never minded Tom. But... there's possibly a volume difference on my part. That might do it."

"Volume difference? What does that even-" Ah. Enlightened, Sherlock asked, "That was a compliment?"

"I'll just go and set him in the hall, shall I?"

"Please."

Later that evening, he got up to relieve himself. Toby oozed in behind him, leapt to the top of the toilet tank, and stared. In the dark, its eyes glowed green.

The cat emitted a quiet, inquisitive, "Mrr?"

Sherlock felt distinctly unnerved. But he finished his business, ruffled the cat's head (it tried to bite him but he was too quick), and left, saying quietly, "I'm on to you now, mate. Plenty of doors that close in this flat."

The cat kept watching him as he went away.

Once one key connection is made, the rest tend to fall into place. It turned out to be as true of cats as it was of other mysteries. The cat hated him. Wished he were dead, but since it couldn't manage that it was simply trying to make him go away, either of his own free will… or because Molly made him depart.

And the bloody beast was clever about it. It was quite possible it might succeed.

Toby stopped physically attacking him, since he outweighed it by more than an order of magnitude and all that it gained from violence was a vigorous spray-bottling from Molly. Instead, it chose more nefarious methods.

Sherlock and Molly would sit on her sofa to watch telly (eventually they would be able to get through an entire film with all their clothes on, but for now Sherlock was quite content with this arrangement). But now, when they did, Toby would sit between them, and by some alchemy would take up all of the space available until the two humans were marooned on opposite ends.

One night, while Molly was cooking dinner, Toby sauntered through the kitchen with a battered L&M in its mouth (and how it had managed that Sherlock would very much have liked to know, since they were in the zipped inner pocket of his coat which was hanging off Molly's coat rack). This had sent Molly into a flurry of frantic googling on nicotine toxicity in cats, and then a disappointed discussion of how she knew it was difficult to give up an addictive habit like smoking but really it would probably kill him and he'd been doing so well with the Champix, what had happened?

The staring never really stopped anymore. If Sherlock was in Molly's flat, he was being watched. It was an oddly demoralizing sensation, similar to dining with his brother.

The cat walked directly in front of him once and Sherlock (entirely accidentally) kicked it square in the ribs in the process of trying not to snap his own neck. Toby had howled and sprinted to Molly, mewling pitifully.

Molly, who was normally quite sensible, had been entirely fooled by this ridiculous act and snapped, "Sherlock!"

Struck by the injustice of getting snapped at when he was completely innocent, Sherlock pointed out in quite a calm tone that the cat was entirely at fault and had clearly set up this scenario in order to ambush and injure him.

Molly got… well, rather sexily sardonic, actually… and said that an animal with a brain the size of a walnut should not in theory be able to successfully trick someone who thought he was the smartest man in London, and that therefore Sherlock should watch where he walked.

Sherlock inquired what exactly did Molly mean by "thought he was," pray?

Molly replied that she meant exactly what he thought she meant and there was no need for him to be so hostile to a sweet and innocent cat just because it had made him feel foolish.

Sherlock had responded by saying that there was such a thing as playing too much to type, and if she truly thought that her hellbeast was located anywhere in the same continent as "sweet" or "innocent" it was no wonder she'd thought Jim Moriarty was appealing date material. After the fact, he acknowledged that this was a regrettable tack to take, since he knew very well that Jim was still a sore point with her.

Molly made a few pungent remarks agreeing about her appalling taste in men and suggested that maybe Sherlock might like to pop his bleeding collar and get out of her flat if he was going to be an ass.

Sherlock had quite agreed with this and had departed but definitely had not put his collar up. They'd made it up afterwards, very pleasantly so… and yet. And yet. Molly had had a point: the cat could not, physically, be clever enough to trick him. It was a question of cubic capacity of the brain. How, therefore, had it managed to provoke two adult human beings who had been entirely happy with one another not thirty seconds previously into an argument?

The enmity wasn't mutual, at least not at first. Sherlock was actually quite fond of animals, though the responsibility involved had put him off owning any as an adult. While he preferred dogs, which were straightforward and loyal, to cats, which were mostly insecure narcissists, he had no objection the species in general. Mary Watson, for example, kept a very pleasant example whose company Sherlock had often enjoyed.

Therefore he sincerely tried to ingratiate himself with the animal. At least until one bitter-cold winter morning, when he was dragged from Molly's comfortable, warm bed by a phone call from Lestrade. The DI could not be trusted to appropriately numerically rank cases and so his "nine" was probably exaggerated but a nice juicy murder involving two pairs of identical twins (one of each set as both victim and suspect) could simply not be neglected.

In the dark, he picked his spare outfit from Molly's closet by feel (as waking her before her alarm went off was one of the few ways Sherlock suspected he could provoke her to murder.) He kissed Molly, very carefully, on the cheek, and dressed in the bathroom. Appropriately garbed, he slipped into the hallway and put on his shoes, at which point he experienced a feeling of horror unique to those who share a house with a cat.

Very carefully, he limped over to the kitchen sink where he used a paper towel to remove the cat sick from his right shoe and sock. It was still warm since Toby, walnut-sized brain notwithstanding, had timed his eructations perfectly.

While Sherlock affected to be nonchalant about his clothes, the plain fact of the matter was that nobody dressed as well as he did simply by accident and getting his ensembles together took massive effort and money. And while he owned several similar pairs of shoes, Toby had somehow managed to vomit in his single most expensive set, the brand new £500 black Yves Saint Laurent oxfords. At his current fee schedule, these shoes represented his post-tax income for several fucking tedious hours doing paid consulting on adultery/druggie children/thieving employees instead of doing what he wanted.

And so, with one damp foot, Sherlock Holmes found himself at a freezing-cold murder scene (barely a four as soon as one examined the dvd player clock, definitely not worth the effort of getting out of bed and forgoing nice sleepy morning sex) fantasizing about how he might kill his girlfriend's cat. Not for the last time.

Not that he would, obviously. Molly would be upset if Toby died or disappeared even if Sherlock could completely exclude himself as a suspect (answer: yes, he could, quite easily). In fact, given the cat's penchant for attacking much larger animals, Sherlock could even picture himself being obliged to come to its rescue, distasteful as the prospect seemed.

But as intellectual exercises went, murdering Toby was a highly satisfactory one.

Molly was having a terrible week.

On Monday, she got a rejection notice for an article that she'd submitted to the Lancet. She'd more or less been expecting that… it was a prestige journal and a long-shot to get into, and she could certainly place the article elsewhere. It was more that the second reviewer had been just so nasty in their rejection notice. They'd criticized everything about it: the writing style, the methodology, and the analysis. They'd stopped short of calling her an idiot straight-out, but it was implied in every sentence.

On Tuesday, she had to conduct an autopsy on an infant. The baby had been born seemingly healthy, but had gone quickly downhill for no obvious reason almost immediately afterwards. She always hated having to deal with children at work… and while normally she got through it by repeating to herself: "This will help them save the next one" the inconclusive nature of her results (maybe genetic, maybe infectious, who the hell could tell?) didn't even give her that satisfaction.

On Wednesday, as Molly was leaving work, her mother rang. A routine checkup had led to further investigation which had led to a diagnosis. Invasive breast cancer, stage 2b. There would be a mastectomy and radiotherapy and chemo. Molly's mother was quite calm at the prospect, saying (fairly) that her prognosis was good and she was optimistic. And so Molly kept her chin up and said reassuring things until her mother rang off.

She got home and unlocked the door to her flat, and there was Sherlock. Her lovely boyfriend, who was so handsome and so clever and so absolutely bloody shit at anything involving emotions. He was staring at Toby over his tented fingers… well, obviously he wasn't staring at Toby, why would he do that? He was probably just doing his mind palace thing. But Toby was in front of him and staring straight back.

When she didn't say anything, he glanced up at her, and seeing something on her face, he frowned, and made as if to speak.

That did it, and even knowing it was a mistake, she flung herself into his arms and started to sob.

Mary, in contrast with Molly, was quite content with the world just now.

She had a pleasant job that she could stop thinking about at the end of each day and that never involved killing anyone. She had an unusually nice baby, currently sitting on the kitchen floor slamming pieces of Tupperware into the tiles with verve and panache. She was married to a man whose company she would enjoy even if she didn't simultaneously want to shag him until his eyes rolled back. There was a pot of homemade Bolognese sauce simmering on the cooker which would be delicious in approximately forty minutes, by which point she was going to be starving.

Literally at the moment she recognized that she was inordinately happy, but before she had the time to think "Uh oh. Something's going to happen," something happened.

Specifically, John came into the kitchen carrying his mobile, and said "Dupin's in the Rue Morgue."

This meant that Sherlock needed help, because, like all men, part of John had never gotten past a mental age of ten. That part of him was the part that liked to play secret agent.

"Do we absolutely have to use the code phrases?" Mary, the actual former secret agent, inquired. But knowing it was a lost cause, she didn't wait for an answer and said, "I suppose you'll be going out, then. Do you want a sandwich to take?"

"Nope. This one's above my pay grade." With that, John handed her his mobile, took the spoon out of her other hand, and addressed himself to the sauce.

Mary read the rather frantic text message, frowned, and poured herself a glass of water. Rue Morgue indeed. She got her own mobile out and sent four texts.

-Let her cry it out and then get her a glass of wine or a cup of tea, whichever she wants.

-Give her some hugs. Run her a nice hot bath and then put her to bed.

-Productive things to say here include "We'll get through this" and "It will be all right" rather than going on Wikipedia and reading her the five-year survival rates or anything like that.

-Tell her I will ring her tomorrow or if she wants, she can call me tonight.

There was a gap of several minutes… an eternity if you knew Sherlock's normal texting habits. She would have bet money he was checking Wikipedia right now. Then:

-Why would I discuss five year survival rates with her while she's upset? They're hardly encouraging when applied to a family member. –SH

-I don't know why you would, but since you are Mr. "Let's talk about grim first trimester statistics for forty year old women who didn't know they were pregnant until ten seconds ago" I thought I should mention it's a bad idea.

-On that occasion I was taken very much aback and not operating with my customary sensitivity. –SH

-Although interestingly enough I have recently learned that your odds of a positive outcome this time are actually somewhat improved, despite the fact that you are even older. Apparently the difference between a primigravida and a woman with a successful pregnancy history and a proven pelvis is significant. –SH

Mary rolled her eyes. He was such a con artist sometimes, but this time she would not fall for it.

-You have not seen me in a month and therefore you are guessing and not deducing. If you want someone who can't tell the difference I can go and fetch John back.

-Incorrect. While I haven't seen you I have seen John and he becomes excessively bug-eyed and Toryish when you are enceinte. It's quite distinctive. -SH

-Let's not tell him, though. You two will be announcing in three weeks anyway, and he'll be so pleased to think he kept a secret from me. –SH

Damn it. She couldn't even tell him he was wrong about the bug-eyed and Toryish thing.

-Is Molly still crying on your shoulder?

-Lap now. –SH

-Then tend to her, you great oik. Did you need anything else?

-Only to give you my congratulations. –SH

Mary chuckled… and deleted the conversation from her phone. It wasn't as though her husband was a snoop or anything, but Sherlock had been right: John would be happier if he thought he was becoming less transparent.

She thought she should go check on the sauce. John tended to oversalt things when left to his own devices.

Mary's advice was always irritatingly correct. Molly had cried herself out and drunk a glass of red wine, but had declined the bath in favor of a shower. Sherlock had laid out her pyjamas… and had cleverly selected the ugly green flannel ones instead of the black satin which were his personal favorites. She'd gotten herself into them, and they were now spooned up, her back against his chest.

He stroked her hair. This was unpleasant, given how damp it still was, but it seemed to be doing the trick. Molly was hiccupping periodically but no longer actually crying.

The bed shook as Toby, who was huge and had none of the grace typically associated with cats, leapt up. In his mouth was a little yellow plastic jingle-ball, his preferred toy of the dozens which Molly had bought for him. He dropped this toy in front of her face with a pathetic little clank, and then gently butted her head with his own.

Sherlock smirked. This would show Molly how selfish and demanding the cat was, demanding her attention for play when she was coping with her own issues. But instead, Molly lifted a hand and scratched Toby's head. The cat bumped up into her hand, and then nestled himself into her belly and sat, making the asthmatic wheeze that was the closest he could come to a purr.

"How come I've got such sweet boys?" Molly said, and sniffled.

Sherlock frowned. Was it possible that Toby was trying, in an ineffectual way, to make Molly feel better?

And was the animal actually succeeding where Sherlock hadn't?

Yes. Damn it. Molly's hiccups were gone and her ragged breathing had been replaced by the deep, regular respiration of sleep.

Since it was barely eight in the evening, Sherlock waited until he was sure Molly was out and then extricated himself from the bed. Toby, instead of immediately leaping into the vacated spot, followed after him. They walked into the kitchen, and Toby sat next to his empty food dish and made a quiet mew. Molly, in her upset, had forgotten to feed him, so Sherlock rummaged through the cabinets until he found the tins of innards in gravy and emptied one into the dish.

Sherlock left Toby to his noisy meal and went into the lounge, where he helped himself to Molly's laptop and began to read his emails. Some ten minutes had gone by when Toby stalked into the room, sat, and stared. As per usual. This time, though, the stare seemed devoid of the flat hostility that had typified previous examples. Instead, it was… assessing. And somehow Sherlock found himself saying, "You and I should be friends, you know. We have at least one common interest."

He felt like the chief ass of the world for giving the "we're not so different, you and I" speech to a cat as if it could possibly understand. It was probably a coincidence that Toby blinked his large amber eyes, yawned, and then walked over to Sherlock and rubbed against the leg of his trousers. Briefly. Then he stalked over to the window and folding himself into a loaf shape, providing Sherlock with an excellent view of his arsehole.

But perhaps, at the end of the day, that was the best you could hope for with cats. And so Sherlock returned to his email.