A/N:

Fill for the following prompt from livejournal:

John suggests that Sherlock should get a pet to help keep him occupied between cases.

John comes home a few days later and is confronted by one of these:

/watch?v=U3A7Qn-06Xc

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John has never really wanted a family. Perhaps this idea stemmed from his parents' general disinterest towards him growing up. Perhaps it was the sight of his sister's marriage falling to shambles. Perhaps it was the war— the destruction, the endings. The goodbyes that would never be said. The tragedy.

Whichever it is, John is quite content by himself. And when the rent needs to be paid, he grudgingly agrees to be the flat mate of one Sherlock Holmes— which turns out to be quite nice, mostly. Other than the gun fights and street chases, it's quite a nice life. And in his opinion, "other than" should be replaced with "especially with."

It's the two of them, fighting crime and, well, as much as Sherlock hates it, saving the day. Fighting a war on the streets of London.

The bachelor's life, apparently, has just come to an end, however. Because as he stares into the thing's eyes, and it stares back, he realizes with a sinking feeling that this is about to make two into three.

And the worst part is it's his fault.

John regrets that day with all of his being, in retrospect. The specific idea that possibly could have possessed him to say such a thing is both elusive and alarming to him.

It hisses at him, fading into a deep set growl. He masters the impulse to return the favor, looking desperately to Sherlock, who is sitting at the table glancing absentmindedly at a microscope.

He purses his lips and continues to stare back at the strange cat. It's wide, as if someone had stretched its head or perhaps even squished the top in its early years. Two stripes lead away from its accusing green eyes, and it seems to only possess two teeth.

And no wonder, he thinks. What an awful attitude it has.

It occurs to John that this is precisely why it holds such a connection with Sherlock. Well, enough of a connection to allow it into their flat. Sherlock is certainly not someone he would call a cat person.

"I see you bought a cat." John raises an eyebrow, and it hisses at him again. He inches back slowly, eyes widening in disbelief.

"Yes," Sherlock murmurs distractedly. "You did tell me to do so."

Yes, yes he did, and oh, how he regrets it.

The incident had occurred a few weeks prior, shortly after Sherlock had finished another case. The criminals and police of London were too slow for Sherlock— within a mere hour of being on the case, the perpetrator was arrested and sent to jail. And Sherlock, being the squirmy child-like creature that he is, had been crouching on the sofa, shouting at the telly for hours on end until John had finally told him, quite firmly, that it was three in the morning, and that any shouting he wished to do had better be done outdoors, a few miles away where they could not rouse him.

This, of course, did nothing to save John's situation. Gripped by the sudden urge to head down to the bar and analyze the crowd there, Sherlock dragged John out the door, only waiting impatiently by the door for about half a second before barging in on him while he was trying to change.

Reddening slightly (a lot, really), John had yanked his arm out of Sherlock's grasp, matching his pace and grumbling under his breath that Sarah would most likely kill him.

And after that, a truckload of events had occurred— Sherlock had realized that there was a smuggling ring trying to sell opium covertly on the streets of London, and so of course there had been the mandatory hour long chase (on foot), calling of the police, and other such matters, and somewhere in the middle of all that, John vaguely remembers having mentioned Sherlock's desperate need for a companion who would be able to keep up with him.

"What?" Sherlock had spun around on the spot, dodging a gunshot and bearing down accusingly at him as he waved his gun around. "Why? I have you, don't I?"

Looking back, it had all been rather sweet, actually. Behind Sherlock's arrogant waving-of-the-gun and leaning-into-the-personal-space had been a rather vulnerable fellow asking if John had finally tired of his company and decided to leave.

"I'm not going anywhere, you twat." John had sighed exasperatedly; leaning forward, he then tugged the gun out of Sherlock's slack grasp, and shot one of their assailants casually. "But I do need sleep, you know. Most humans do." Dodging another bullet, he grabbed Sherlock's tie and yanked him around the corner, taking cover before folding his arms crossly.

"Unreasonable, then." Sherlock had breathed in that particularly deep, breathy way that he did. "If all or most humans do, then the odds of finding one who does not will be slim, even for me."

"Get a pet or something, then," John had muttered irritably— and here the opium gang members had flipped rather dramatically over a rail behind them and begun to open fire again, so the matter was dropped, and eventually John had simply assumed that Sherlock had forgotten about it (unlikely), or ignored his advice (highly likely).

But John sees now that Sherlock most certainly hadn't forgotten. And while he is quite pleased that his flat-mate is possibly taking his opinions into account at last, he is less than thrilled that this particular thought is the one Sherlock decided to latch on to.

The cat hisses at him. John hisses back. Manners be damned.

"His name is Entropy," Sherlock murmurs, and John starts as Sherlock practically breathes into the back of his neck. For a split second, John considers the fact that Sherlock's owning a cat may (if even possible) decrease his knowledge on the subject of personal space; eyeing the cat's vicious claws and smile, he instantly knows this to be improbable. This is certainly not a cat that will encourage cuddling. The thought of Sherlock trying and failing to cuddle makes it difficult to hold back a smile, but he does so, frowning acutely in his attempt. The cat frowns back, lamp-like green eyes narrowing.

"Ah," he replies, carefully taking an even step backwards— between the cat and Sherlock, he will take Sherlock any day. Sherlock does not move. "I… I see. Well— Hang on. Entropy?"

He feels the vibrations dancing along his back as Sherlock replies. "Entropy."

John raises his head and juts his jaw to the side in incredulity, turning at the waist somewhat to stare up at Sherlock. It is an uncomfortable position, but he wants answers and would prefer not to go any closer to the cat than necessary. "You've named your…cat… after a scientific process?"

"A chemical process, John." Creases form in Sherlock's brow as he furrows it earnestly. "I like Chemistry, you know." There is an awkward pause as John twists back around and glances around the apartment pointedly as if to say that yes, he knows Sherlock is incredibly fond of Chemistry; disturbingly so, going by their kitchen table, littered with burns and various stains.

It's quite interesting, the way Sherlock can pick out an obscure missing nebula in a painting, see dirt under the nails of people on the other side of the room, and pick out specks on the backs of a dead woman's legs, and yet not notice the mess he leaves behind as he carries out and grows bored with his many experiments.

Sherlock sniffs properly, and John is all at once struck by the thought that Sherlock is rather like a nine year old. He doesn't know whether to be more worried at this revelation, or at the fact that this has occurred to him quite often and on a regular basis.

"It's a metaphor," Sherlock mumbles, and John looks up suddenly at the new experience that is Sherlock mumbling. Sherlock rarely does such a thing— he is loud and opinionated, shouting his thoughts to cover the overwhelming silence (and stupidity) of the entire world around him. To mumble is beneath him. Or so John thought.

"A metaphor." John repeats this. The cat hisses at him, and yet again he is met with the urge to tug its collar and push it out a nearby door.

Or window.

It hisses again. He glares at it. This is ineffective.

"Yes. Entropy, John, is the tendency—"

"Tendency of objects to move towards disorder, yes," John recites. "I am a doctor. I did learn this stuff."

"A study in chaos," Sherlock muses, wrapping his dressing gown more firmly against himself and swishing away to his armchair before dropping into it gracelessly. "A removal of order. Much like us."

"Pardon?" John actually raises his right hand to his ear, certain that he has misheard, and Sherlock rolls his eyes like always, sighing as if filled to the brim with John's tedious stupidity, and closes his eyes. John sighs; clearly he should not expect any sort of response. "Sherlock?"

Sherlock says nothing, and John glances back at the cat. Is it just him or does it seem to be drawing closer?

"Sherlock, where shall it—?"

"He."

"—pardon?"

"Where shall he, John. He shall sleep in my room."

John blinks. Blinks again. Blinks a third time. The cat is sleeping in Sherlock's room. Millions of pictures of Sherlock cuddling Entropy rise unbidden in John's mind, and he cannot decide whether they are cute or disturbingly unnatural.

"As long as I don't have to deal with its…" John waves vaguely, and Sherlock, annoyed, says something about litter boxes and the market. "Right then. Also, you know what cats like, Sherlock? Milk." Sherlock sits up, slightly alarmed, and opens his mouth, but John beats him. "That's settled then. Goodnight, Sherlock!"

John all but sprints to his room, glancing back only once. Entropy is strutting off the table towards Sherlock, who is eyeing the cat with mild disinterest. The cat's expression mirrors his as it creeps towards the thin detective before climbing on his lap and curling up. John watches in mild fascination as the pair continue to maintain eye contact; Sherlock narrows his eyes before reaching to pet the cat.

It's a weird battle of wits, John can't help but think. It's like they're challenging each other.

Nevertheless, the sight of the cat cuddling up to Sherlock makes a smile rise to John's lips, and before he can wonder why, one single thought crosses his mind—

Family.

Jesus, they're similar enough to be.

He shrugs and trudges up the stairs to sleep.

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A/N: I don't know if I should continue this, or if there's even anything I would continue it with. Perhaps you could give me some idea in a review? That would be rather lovely.

Thanks for reading!

I own none of the characters. Well, except Entropy.

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