Disclaimer: Anything you recognize, I'm just borrowing for fun.

The Sound of Silence

The first time Sherlock realizes something is wrong, it's because John is furious with him.

Nothing strange with that, happens fairly often. What puzzles Sherlock is that this time, he's done nothing to warrant it.

John isn't prone to getting mad at him without just cause (admittedly, he does not have many chances of it, as Sherlock provides him with plenty of just causes on a regular basis).

Yet this time he's positively fuming.

And Sherlock has no clue why.

Most unusual.

He focuses on his flatmate, who's shouting: "I'm not stupid, Sherlock! Bullets were fired from my gun, and not by me!"

Sherlock frowns minutely, then jumps up and pilfers John's gun from his hand and examines it keenly; he easily ignores his friend's rant, too intent on comparing the powder marks (unusual – John always cleans his weapon religiously) and the brass rings to the rear of the ejection port, with the last image he has stored in his Mind Palace.

Facts: He hasn't used the gun recently. Apparently, neither has John; yet the gun was obviously used.

Conclusion: someone else fired John's gun, for unknown reasons, then somehow put it back. Without them noticing.

How… interesting.

The second time, it happens at a crime scene.

There is something inconsistent in the evidence under his very eyes. He has processed it all twice, he's interrogated the witness (culprit) to his satisfaction, he knows he should have figured out everything by now, but something still eludes him. Something his senses are telling him, but he can't fit in what his mind has deduced.

He worries at it like a dog with a bone, until he reaches the only possible conclusion.

"There was someone else here."

His voice echoes slightly in the warehouse, forensic experts and cops falling silent and craning their necks, waiting for his usual cascade of deductions.

He doesn't oblige.

He is uncharacteristically unsure of himself and not even John's quiet questions, usually such a conductor of light, can help this time.

There was someone else here. Someone who was almost certainly injured (the way those bales of fabric are scattered indicates an adult body impacting them), possibly killed (unlikely – no traces of blood not belonging to the body on the floor anywhere; bullet-proof vest perhaps?).

Someone the witness (culprit) doesn't remember.

Someone, furthermore, who must have been taken away by someone else, since they are not to be found here. Someone else who is also not in the witness' (culprit's) memory.

He's tempted to class it as impossible, but the meaning of the word is not as comfortable a limit as it used to be.

"Well?" demands Lestrade impatiently, looking at Sherlock with annoyance and trust. "Was it the perpetrator? Where should we look for him?"

"The witness didn't mention anyone else," interjects Donovan, crossing her arms defiantly. "I thought you said he isn't lying?"

He isn't. Sherlock knows this. Just like he knows the 'witness' shot the dead man on the floor, but said dead man shot someone else (no other way to account for the missing bullets and their obvious trajectory). It's clear to him.

And he can't prove any of it.

The gun thing happens again, but this time he wasn't even home. Yet Mrs. Hudson meets him on the stairs with a disappointed tinge to her usual fondness.

"Oh, Sherlock!" she reproaches gently. "Have you been shooting the walls again?"

"No, I haven't," he rebukes absently.

"Well I doubt it was John!" she huffs. Then, shaking a finger at him: "It's coming out of your rent!"

Sherlock frowns, and files the incident away. Not enough data yet.

The third time, he discovers the discrepancy in his own Mind Palace and almost panics.

They had been working for a couple of days on a murder case involving art students, serial burglaries and pottery figures of Margaret Thatcher, that had turned out to be disappointingly simple. He's solved it. He shouldn't be feeling like there is something left to work out, because there isn't. Or is there?

He needs time to think, so he has deliberately annoyed John to the point where he's left the tea unfinished and gone to the pub, shouting something about leaving Sherlock to educate the frozen turkey on the many ways to get away with murder.

Sherlock ignores the suggestion, of course. He has no interest for unfinished tea, turkeys, or educating idiots.

He arranges himself carefully on the couch he so loves and starts going over all the data he's collected for this last case, determined to find the inconsistency that is troubling him and the explanation for it.

It is probably hours later when he is finally certain that he has isolated the right frame of time – a stakeout the previous night, at one of two possible addresses where the murder would go. Quite a boring endeavour he endured, until John called him with the news that he had found their target and was chasing him.

Nothing had happened.

He frowns.

Correction: he doesn't remember anything significant happening while he was waiting in the dark. His memory is clear and devoid of anything but darkness and a silent, empty flat. Why, then, does he feel so uncertain about it?

He carefully examines his memory of the episode again and frowns some more.

If he looks at it like he would a crime scene, then he can see obvious traces of a presence there. But not the presence itself.

Someone was there, with him.

He can't possibly have missed it.

He doesn't appear to have noticed it.

He feels panic mounting and fights it viciously down.

Someone was there and he can't remember them.

This is not good.

John is back and making tea. Sherlock approves. In the privacy of his mind, he can admit that the familiar sounds of his friend's puttering and muttering are soothing.

He can think of the situation more calmly now.

Fact: someone was present in a room Sherlock was in and cannot be remembered. This… has happened before. He dugs out the instances he's filed away – the gun incidents, the missing victim – and looks at them in light of his working hypothesis. He'll need to experiment, of course, but some conclusions can already be tentatively reached.

He nods to himself slightly. He is starting to paint a very clear picture of the situation and he does not like it one bit.

"What are you working on?" asks John when he fails to complain about the lack of interesting cases for a few days.

"Too soon to tell," he answers briefly.

He knows why he doesn't want to explain to John his findings.

He feels too raw, too insecure about the situation. His mind is being compromised and he is too close to the brink of real fear to want to expose himself, expose weakness, even to his friend.

For all that John is patient, however, he is also a worrier. It isn't long before he's demanding answers more and more insistently. He never likes it when Sherlock keeps secrets – he claims it increases the probabilities of the detective's violent demise unacceptably.

When a call from Lestrade about a triple murder gets turned down, John explodes.

It's ugly.

Sherlock bristles and goes cold and lashes out with sarcasm and retreats in himself – classic defence mechanisms, he knows it and he hates it, but he can't help it – and John shouts abuse and brings up old grievances and hits where it hurts in spite of Sherlock's armour of supposed indifference and it could all go to hell, Sherlock can see it (he's a genius after all), he could lose John over this (unacceptable) or be forced to admit his own weaknesses (also unacceptable) but then somehow Baskerville gets mentioned and Sherlock's brain screeches to a halt.

John doesn't realize of course (he's an idiot) and goes on shouting, but Sherlock isn't reacting anymore, he's thinking. In fact, his entire thought process is derailed and then rights itself on different tracks – better tracks – faster than it takes John to realize Sherlock is oddly silent.

In Baskerville, John would have let Sherlock experiment on him if he had asked. If he asked now, John wouldn't judge, he would volunteer to help him. John is always willing to do that, isn't he? More importantly, John is always able to help him.

Some people who aren't geniuses have an amazing ability to stimulate it in others, he remembers saying.

He would have solved the Baskerville case much sooner had he not indulged in panic (No, no, no, it was more than that, John. It was doubt. I felt doubt) and John knows how to deal with that kind of thing better than he does.

I'd be lost without my blogger.

John never criticizes Sherlock for being human (weak) because he already believes (knows) he is and never expects perfection (even when Sherlock himself does).

No no, don't mention the unsolved ones. - People want to know you're human, Sherlock.

He doesn't shy away from danger.

Wanna see some more? - Oh god yes.

And he never doubts Sherlock.

That. Was amazing.

Even when he isn't impressed with him.

Because you're an idiot.

John is his friend.

I've just got one.

So maybe he can afford to trust him after all.

Abruptly, he relents and tells John everything - the doctor's jaw hanging is kind of satisfying - shares his suspicions and observations and conclusions, and then he is profoundly glad he did so, because John lets go of his anger entirely and just frowns calmly in that way of his.

"Well, talk about snafu," the former soldier mutters. "How are you going to find whoever's doing this?"

"Indirectly. Obvious. I must pinpoint the wheres and whens, deduce the hows, and from there retrace the whos; and I'll have to do that looking at the absence of clues rather than their presence." Sherlock paces, nervous energy coursing through him. "It's like in a forest, John. When every sound is important, but the sound of silence is the one that tells you the most."

"That's brilliant," says John, as usual.

Sherlock hesitates. Dares he confess? He doesn't want to, but. "I don't know if it'll work," he admits in a rush.

"Doesn't matter," is John's calm verdict. "You'll come up with something else if it doesn't. You can do it, Sherlock. Nobody can hide from you."

Warmth spreads through Sherlock's chest.

He begins a series of systematic observations and fills the in-between times with extended research ranging from minor police reports to the blogs of conspiracy theorists.

He compiles a list of possibly related cases, organized by relevance.

He hacks more databases than usual (Mycroft makes noises but he ignores him easily) and studies the latest cutting edge technologies (nothing seems even remotely capable of inducing the effect he has observed) and the most secret research avenues (correcting a mistake or two here and there).

He explores areas of London, attempting to map the Presence's movements or to draw it out, or both; he drags John with him at apparent random, monitoring his friend's reactions as well as his own, and spends days going over and over his memories to identify all instances of incongruence.

John complains about useless things like food and sleep, but Sherlock has experience in tuning him out.

He is scared and elated in equal measure.

Direct observation – his most potent tool – has been taken from him. That doesn't mean he's powerless. Oh, no. The Game has more difficult rules this time, but he will still win.

It is possible to recreate something missing by the hole it left.

Sherlock will regain his memories, developing them from their negative if need be.

It takes him a while to be sure that his progress is being slowed down not by a natural phenomenon or an unintended side-effect of some technology, but by someone actively tampering with his mind.

The repeated memory loss is too consistent with the presence of someone he hasn't figured out yet, to be anything other than deliberate. He has checked his Mind Palace thoroughly and it is untouched except for the missing Presence, glaringly evident now that he knows to look for it.

Conclusion: someone is deleting things from his mental hard drive without his permission.

Fury and fear consume him, but they are as cold as ice. His brother would be proud.

It takes him much less time to realize that if John is with him, whenever his – their – mind is tampered with, the gun gets shot without either of them remembering. Few observations are enough to confirm that the shooter is always John, even if he doesn't know it afterwards.

On one occasion, when he arranges for John not to have the gun with him (because Sherlock is a scientist and very thorough in the design of his experiments), a crowbar appears to have been used (rather effectively), again without him or John having any memory of the fact.

Obviously, whoever is altering their memories provokes a visceral, violent reaction in his friend.

Sherlock however isn't affected in quite the same way. Why? Because he is not a soldier? Because John is not a genius? Possibly. Or possibly for a completely unrelated reason. Not enough data.

"Whatever it is, it's useful," proclaims John.

When Sherlock looks at him uncomprehending, the doctor rolls his eyes. "This Presence is obviously hostile. I mean, it's messing with our minds! Who knows what else it can do? It's good that I can fight it even if I don't know it."

Then he points an admonishing finger at Sherlock: "And that means you need me to stick by you until this is all over. Don't go wandering off on your own."

He glares for good measure, but for once, Sherlock has no intention of disobeying. Not when the integrity of his mind is on the line.

Most of the time, Sherlock is in high spirits. He relishes the challenge.

Indirect observation has already brought him closer to his mysterious opponent than it was likely expected.

When the panic rears his ugly head or depression at the lack of results creeps up on him, John grounds him with his calm assessment of the situation (and by feeding him tea and biscuits, which Sherlock will never admit make him feel better).

John is right. He is making progress. He might not yet know what the Presence is, but he knows it's there and he's building up a fairly clear idea of how it moves and what it can do. In spite of his memories having been altered on more occasions than he cares to contemplate.

There is no reason to panic.

He merely needs to widen his search and rely on memory of the smallest details – those less likely to be affected by this mind control – ignoring the big picture, which is almost certainly compromised.

That, and John's strange reaction. Why does the doctor invariably react so violently to the Presence, when he himself doesn't? It is important, he knows it is. Part of the puzzle. He needs to figure it out. Where does this piece fit?

Then the Presence makes a bolder move in their very flat.

221B Baker Street looks exactly like usual, the well-worn couch, the horrible wallpaper, the books and papers and abandoned teacups, Sherlock's Persian slipper and John's Union Jack pillow, the smiley on the wall and the skull on the mantelpiece: nothing suggests anything strange might be going on.

But one of his beckers has been hurled through the room (improvised weapon, Sherlock deduces at once) and John finds a black mark on his right arm.

A simple line, obviously made by a marker pen. It is the matter of a moment for Sherlock to locate said marker pen, abandoned on the carpet as if John had let it fall after forgetting he'd used it. The angle at which it fell, how far it rolled, everything tells Sherlock that it was, indeed, John who used it and threw the becker at something (or someone).

He finishes rattling off his deductions and abruptly realizes he is no longer holding the marker.

John is.

And the marks on his arm are two.

"It's like I'm keeping count of something," says John. "But why can't I remember? This isn't memory modification, we're forgetting as it happens!"

"I did not notice," whispers Sherlock, eyes fixed on the two black marks. "None of it."

Then his voice rises with anxiety tinged with hysteria, firmly leashed by his formidable self-control, but lurking at the edges anyway.

"John, I did not notice. It happened right before my eyes and I did not notice!"

"All right, just- just keep calm, ok? We'll figure this out."

John is halfway through the room and looking slightly confused, as if he's forgotten why he's moving towards his bedroom (Sherlock suspects he's going for his gun. Reasonable. He hasn't seen him move. Worrisome).

"We'll just… we have to, I don't know, think this-"

There is a new mark on John's arm and he's now holding the poker.

"-through properly, yeah?"

John is making a creditable effort to sound logical and calm, but Sherlock knows what's going on. The Presence is here.

Sherlock turns on himself, slowly, observing their sitting room.

Like at that crime scene, like in his Mind Palace, there are traces of a presence he can deduce but not see.

John is right. The memory loss is happening as they go along. He has to make a continuous effort to re-deduce things he already noticed and interpreted, because he is always on the brink of forgetting.

He knows the Presence is here. It has to be.

He pivots around, knowing it's useless but unable to stop himself, scanning the room over and over. He hates this. He knows, he knows that things are happening under his very nose.

And he cannot see.

"Is this how you feel all the time?" he asks randomly. "It's awful."

John, who is suddenly back by Sherlock's side, rolls his eyes.

Then freezes.

Silently, he points to Sherlock's hand.

The detective has completed a full circle and there is a mark on his left hand.

Not marker pen – a regular, inexpensive ballpoint pen, lurid blue.

John has a fourth black mark on his right arm. The marker pen has again fallen to the carpet.

Sherlock's hand searches his pocket and sure enough, it closes over a pen he does not remember putting there.

He closes his eyes, forcing himself to remember. Yes. Blue ballpoint pen. It was on the table behind him. Obviously, he picked it up, marked his hand and slipped it in his pocket.

And he does not remember any of it.

"What does it mean?" asks John, voice thick with worry.

Sherlock's eyes snap open.

"They're here!" he declares triumphantly. "They are what we are keeping track of!"

"What? Who?!"

"I don't know. The Presence. John, you were right! It isn't memory modification. They have the power to alter our memories as they form, that's how they hide."

It sounds absurd, but when the impossible has been eliminated... a proposition that is growing ever more difficult...

"Brilliant," he can't help but breathe.

John is nodding slowly. "Alien?" he asks grimly.

Sherlock's smile is shark-like: "Most likely."

He barges into Mycroft's office and jauntily ignores his brother's irritation, slapping a file of his findings (painstakingly compiled and, finally, complete – as much as it is within Sherlock's power) onto his desk.

"There is," he summarizes with gusto, "a race of aliens capable of erasing our memory of their very existence. And most of us are wired to destroy them."

He thoroughly enjoys the way his brother freezes and forces himself into stillness, into impassivity. Sherlock doesn't need expressions to read Mycroft's reactions. The twitch of his eyes is more than enough to telegraph his worry and his annoyance.

Feigning reluctance, Mycroft examines the file.

Sherlock doesn't bother voicing his observations and conclusions. Mycroft never appreciates his showmanship and it's not like he needs it. He's – Sherlock admits it grudgingly, but admits it – likely to reach the right conclusions faster than Sherlock himself.

"Something changed in 1969," he points out, however, just because. "Not enough data on the what. But instances of killings and violent reactions to the Presences only start then."

"Yes, I can see that." Mycroft frowns minutely, his body language imperceptibly stiffening.

It is enough for Sherlock.

His brother will never admit it, but the younger Holmes knows he is impressed.

He whirls to leave, not giving away his satisfaction.

"John, let's go!"

"The Moon landing," Mycroft informs them a few days later, arranging his umbrella against the armchair he has appropriated over Sherlock's token protest and accepting the cup of tea John is offering as a matter of course.

They stare at him.

"Careful cross-examination of quite a lot of data indicated the famous Apollo 11 footage as the pivotal point inciting violence against the Presences."

"Apollo 11?" asks Sherlock blankly.

"I'll tell you later," mutters John with an amused smile.

"Careful examination of the video itself," goes on Mycroft, ignoring their byplay, "proved the existence of a subliminal message inserted in it."

Sherlock's eyes are on fire with interest.

"We cannot remember it, but anyone exposed to it reacts violently to the Presences. Including me," his brother concludes with a grimace.

John stifles his guffaw with tea, probably picturing Mycroft's umbrella buried in the mysterious aliens' eye-sockets. (Do they have eye-sockets? Not enough data.) Sherlock sees no reason to hide his own grin.

Mycroft purses his lips at them, but goes on: "Indirect observation of the Presences indicates a marked reduction in their – well, not sightings, I suppose the word is quite inappropriate."

"Indeed," murmurs Sherlock, fingers going to his usual tented pose as if on their own.

"You were able to deduce this?" asks John, sounding beyond impressed.

Mycroft's face is blanker than usual as he sips his tea and gives him a tight smile: "Not... exactly. Our attempts at investigation caught the eye of an American, Canton Everett Delaware III."

John looks uncomprehending, but Sherlock grasps it at once: "He was responsible for the change in 1969."

"Part of a group that arranged it, yes. An interesting man."

"High praise, coming from you," smiles John.

Mycroft hands his empty teacup back and gets up, fussing with his jacket. "I have already ensured the footage is compulsory in every school of the European Union," he says casually. "Delaware naturally did the same in the USA. It will take some time to arrange it in the rest of the world, but I am confident the threat of the Presences will be dealt with entirely within two or three generations at the most."

Sherlock ignores this, even as John sputters a little in the background. Mycroft in British Government mode is nothing unusual after all.

"Incidentally, Delaware calls them the Silence."

This gets Mycroft an eyebrow raised in interest. Knowledge is knowledge, after all.

"He claims them to be genetically engineered priests able to use post-hypnotic suggestion to manipulate other species into doing their bidding, as well as erase all traces of their existence from one's memory after an individual looks away from them, as we know. Selected labs are being... encouraged, to provide us with technology that will remedy this particular problem."

Mycroft is already on the doorstep when he tosses back: "Delaware wishes to meet you. You impressed him beyond words. Apparently, in all the years the Silence have been on Earth, only the Doctor could deduce their existence."

Sherlock doesn't bother to hide his smugness. At all.