Events in this chapter correspond with those of chapter 24 of the companion piece "Closed Record".

1 - Five Hundred and One

The streets are getting dark when he leaves the building with the convenient lavatory. Roughing it to skip from Mycroft's radar is fine by him, although with his brother's continuous climb up the obscure ladder of the truly powerful, eluding him has become ridiculously more laborious than it was twenty, or even ten, years ago. Returning to Molly was out of the question, for several reasons. Hell, he dares not even stay under the same bridge for two nights.

As he steps on the gritty concrete, an icy autumn wind lifts and swirls the remnants, not of nature but civilisation, on the ground. Food wrappings (bought at the vending machine on the ground floor of the office building), paper handkerchiefs (source indeterminable without chemical analyses – not that he'd care much to rely on a sample of snot), a drinking straw from a nearby cocktail bar (used in something containing curaçao), a plastic bag (from a cheap boutique down the street) blown into the air like some mini-balloon, a neon-pink little something that it takes him a second to recognise as a fingernail. An artificial one, he supposes, although, in close proximity to hospitals, you can find strange things, at times.

Speaking of strange things. He eyes the bad replica of nineteenth century clothing of the couple overtaking him in his (apparently) leisurely stroll, sneering at the zipper down the woman's back, and the polyester-sheen of the gentleman's frock coat. If people wanted to dress up as something they were not… Hell, why should he even think about the bad taste and historical ignorance of people. So as to not to have to think about anything of importance, of course…

Such as: You cannot prove that something does not exist.

You cannot prove that zippers did not exist in ladies' costumes of the 1890ies. You cannot prove aliens did not land on Earth four thousand years back and built the pyramids. You cannot prove Atlantis had not existed.

Non-existence is logically unprovable.

Mathematically speaking, he knows, that is too simplistic, not an absolute statement. You can prove, in a set frame of axioms, that certain elements cannot solve certain equations; you can prove that no rational number exists to solve x²=2. So simple.

But a solution does exist, nonetheless. It is not even that mathematicians had to willfully expand the defining framework, it… evolved. By asking questions that aim outside of the given universe, that same universe forms new parts, of necessity and the laws of ultimate, transcendental logic. Irrational numbers, for all their un-endearing name, are beautiful things that demonstrate the superiority of logic like few things do.

So you can rule out existence only when you completely know, or when it is in your power to define, the referential framework.

But it is not he who dictated this reality's axioms. (Though the fact that he is walking this street, in this very moment, means he has bent the rules set by Moriarty.) Oh, he has learnt very much about the game. The intelligence he has gathered over the past five hundred days are shining in his mind like a beautiful, intricate, complex spider's web; yet, for all that he knows what governs Morarty's gossamer network, there can be no doubt that the dead man was the only one (if anyone) who had fully grasped the fundamental laws that govern his very own universe.

It is not proof that something does not exist, that you cannot find evidence for it.

Five hundred days of fruitless search, of interminable deductive sequences, have not yielded anything tangible. And while Sherlock tends to ascribe meaning to that fact, it is proof of nothing at all.

.

It is a testimony to the degree of his preoccupation, that he catches on to the current date only, when he sees a slip of a girl (Long-term anorexic. See her teeth? No drugs, though. Ring imprint on left ring finger. So, dark circles under her eyes and bad complexion due to unfaithful boyfriend.) dressed in a decidedly inappropriate skimpy and torn dress (hoping to remedy the boyfriendless situation), sporting an artificial slash, fashioned from latex and dark red nail polish for blood, on her right cheek. He stifles the sudden, utterly unexpected urge to snort. It is the 31st of October, of all days...

Tonight, as folklore goes, the boundaries between the worlds are penetrable, the dead can escape wherever they are supposed to be contained. Or residing. He frowns, wondering what the accurate, ecclesiastical (esoteric) technical term is. In ancient times this was no night of joy and feasts. People had been afraid of the return of dead people then. Had buried them with their shoes interchanged and their knives dulled.

It is a good thing, that John-

There surely are a great number of people that he would not care to see come back to life. Moriarty's ghost is haunting him enough as it is, and – although he can to the best of his memory not recall ever having seen the man laugh – it is always laughing at him. About some private joke he is afraid he is starting to understand now.

Ghosts, of course, are another of those things whose non-existence have shown itself to be impossible to prove.

He has become a ghost, too, in all meaningful respects. Although he, arguably, lacks the distinctive feature of having died. Which is what makes the mistake he knows he is about to make possible, of course. A mistake he has avoided making for five hundred days.

If it is a mistake.

Please, don't be dead. For me. John's voice echoes in his head, hollow. Frowning, he wonders if he had not overestimated John's rationality when it came to the non-existence of ghosts.

Wonder about your own rationality, why don't you.

Point taken.

You ought to go.

I surely ought not.

We wouldn't be having this conversation if you were convinced of that.

It is likely to get us both killed.

Is that why you don't go, though?

Of course it is. Is it?

He is not going to return before he has got conclusive evidence that the danger is past. Sherlock?

But proving something doesn't exist is still impossible, of course. So that day might well be never.

Infinity is another mathematical concept he rather likes. After all, he's kept himself going by the comforting certainty of the non-Euclidean imaginary point...

.

Three days ago now, the equation was altered. Not by the dead man peacefully being annihilated chemically in the ground somewhere, obviously.

Disappointment is not the issue. It is the possible reach of effects; could the transformation mean that what he has steadfastly told himself is running on parallel course, is in fact following skew lines?

The dread that ensues from the new pieces of information (or high treason) has driven him away from the place where he knows he ought to be. Finishing the job. Finding a killer. A killer that might finally lead them - lead him - to Moran.

For three days, he has been re-assessing the entire situation, travelling again all the major lines of reasoning that led to his leaving Baker Street, leaving his life. He arrived over and over again at the conclusion that he is taking the logical course. That he still has to do this, save John by keeping away, removing himself as far as possible from him – and for all this unchanged and absolute awareness Sherlock is afraid that he cannot do it anymore. Because hoping for an intersect to happen is not enough to go on.

He is worn to the bone. The – obejctively - continuous passing of time has neither steeled his resolve nor, as he had been half hoping, effectuated a decrease in his wish to return. It has merely worn him down, exhausted his strength of will and is, right now, eroding the pride that is all that has kept him going for some time now. All that is left is his sheer stubbornness, a natural force to be reckoned with, sure, but not enough to keep him on course any longer, now.

Because you can never prove that something does not exist.

What if that is exactly how this was meant to work?

The moment he realised what the transformative revelation means with regard to the probability of this hypothesis – which he disregarded before - was the second, the very instant that he knew he was fucked.

Mrs Hudson slaps him hard across the cheek, leaving a stinging imprint on his skin, and dissolves into a fit of… rage, after that.

He had prepared himself for tears on her part, he had resigned himself to letting her embrace him, was willing to offer comfort in a far more forthcoming manner than he was usually comfortable with, or inclined to.

Now he is standing just inside the hallway at the backdoor, stunned, and watching Mrs Hudson take several steps back, ranting at him. It takes a moment to register, what exactly she is saying.

"How could you?" Nothing unexpected there. "Sherlock! He's a good man, he's the only one I've ever seen you happy with. How on earth could you do this to him?" The elderly lady's eyes are still dry, and they are blazing with fury. "It almost killed him. I expected to find him dead upstairs one morning."

His face must be rather alarming, or maybe she is running out of steam, because Mrs Hudson eventually turns her back and leads the way to her kitchen, leaving the door open for him. She offers nothing by the way of a late night snack, though, simply sits down, drawing her dressing gown close to her, and stares at him. "So, what have you got to say, Sherlock?"

"Is he at home?" he finally asks.

"Even if he was, you can't –" Mrs Hudson's face crumples, and she suddenly loses her composure.

Sherlock puts his hand tentatively on her shoulder but she swats it away and puts her face in her hands. "Go away," she sniffs.

.

She had not told him where to go. She had not ordered him to leave her house, either.

The stair creaks. The scratches in the wallpaper are fainter, half-healed by some glue. The window looking out to the backyard has been cleaned recently. The door at the top landing is open, and the step through it like a step out of a frame that he's been living in for seventeen months. This is a mistake, the light switch whispers to him, when it allows him to see. But he is already in the middle of the room, trying to make sense of anything he sees (books on politics, not something John has ever shown an interest in, so who left them in a pile next to the sofa, who has been sleeping on his sofa, because it has been used as a bed frequently, why is the ashtray there, has John taken up smoking, what are those print-outs about the Iraq War and the fall of Baghdad doing on the table, where has the skull gone again. how can so little have changed, how is that even possible.), when panic hits him.

Then, a key is being turned, no voices, just a pattern of steps, and a cane. A creak. More steps. The door he inadvertently half closed behind him swings open again.

He watches, anxiety buzzing in his ears like bees, the impressions he is perceiving going straight through his brain to the part of him he still refuses to call his heart. It seems to mean that he cannot make sense of what he sees, in his usually instant, analytical manner.

John stills at the sight of him. He stands preternaturally still, frozen, apart from his lips opening in a sudden need for air. His lids slide down slowly, and slightly out of sync with each other, the very picture of shock. And then his lips start trembling – it is like watching his face, this so much missed – and oddly changed – face crumble. Tears rush to his eyes, spilling over, running down cheeks and chin and falling in one single instance.

Sherlock has never felt as shocked himself as he does now, taking in this display of... pain. He cannot be responsible for this, for all this, surely. He is not a person anyone... anyone... His thoughts are stuck in confused waters, too deep for him. It has never occurred to him that this might be the kind of hurt John is going through. Because of him.

John squeezes his eyes shut, fighting for air now in a desperate, hitching rhythm, never able to draw more than a tiny bit of breath into his lungs, like something was blocking his throat. Or choking him.

After several more attempts to draw air into his lungs, all the while those terrible choking noises like blows to Sherlock's stomach, John folds in on himself like a house of cards, silently and elegantly collapsing for good.

.

It is not a case of reality lagging behind an imagined course of events. It is like an alternate reality where he is playing a role he doesn't recognise himself in, doing things he could not have scripted for himself. What they are, or why he is doing them, he only has time to consider later, when John has fallen asleep in the way other people lose consciousness.

He understands one thing immediately, though, the second John's fingers catch his wrist (a gesture so simple he doesn't even question its legitimacy) – instantly tethering him, body and mind. Tethering should make him want to recoil and shake himself free, but the only feeling it does evoke is the instinct that he has, indeed, returned home.

He has forsook feeling connected for as long as he remembers being capable of thinking about such things. Keeping afloat on a cushion of superiority that he knows exists – enabling him to forego what others call essential to a good life, and condemning him to the same thing – led him into a dead-end, and quite early in his life. Total independence, as advantageous as it was in pure thought and intellect, brought on a personal destructive impetus Sherlock has never felt compelled to really examine.

It did a good deal of damage to some of his tenets (he would never willingly call beliefs) but he found a solution when he first decided to... tether his mind to a specific cause, for the first time consciously imposing any kind of order to his rampant mind, really. The Work.

He had never imagined a reason for, or the possibility of, tethering it to a person.

Keeping vigil that night, sitting on the floor against the sofa, he finally sees that he was caught in a chain-reaction, domino pieces falling, inexorably, one after the other. He recognises it now, two times five hundred days after. One thing led to another, within and without.

He loves watching the pieces falling around him.

He hates the pieces falling inside just as uncontrollably. But fallen they have, and the logic to the process is undeniable now.

Caring is not an advantage. Mycroft has never said anything more accurate, Sherlock realises. Maybe it is one true thing he's ever said to him in their lives. Watching John now, he understands for the first time, that there is no choice, though, as he has so long believed. You cannot decide for yourself whether or not you care about certain people. He could not, and John couldn't either, or he would surely not have chosen this.

.

When he wakes to the dim November light, John is gone. Just like that. And Sherlock knows that is not good at all.