Author's note: This is for the eleventh Let's Write Sherlock Challenge on tumblr: "Create a story in a fantastical alternate universe using the following prompt: "The dead body was the least of their worries."" I chose a Science Fiction AU – I love the genre.

I don't own anything, please review.

It happened gradually, slowly, so slowly, so gradually that no one noticed until it was done.

Not even Sherlock Holmes.

Someone behaving a little different for a few days until he "snapped out of it"; a politician making an insane statement before publically apologizing; pets crying out when their owner entered his home and then calming down.

Quietly, surely, they made their way unto Earth.

No one knew whence they came, and no one would ever know. They watched the world, watched it as it turned and made its way around the sun, and decided it was theirs, and thus it began.

It turned out to be surprisingly easy, or at least that's what the messages the consulting detective was to translate later in a dark room surrounded by ruins said.

Men were simple creatures, and it wasn't difficult to create duplicates. It wasn't difficult to make men disappear and introduce the duplicate in their place. Barely anyone realized that the friend, the colleague, the partner they'd talked to yesterday had been replaced. And those that felt something was wrong – there were always more duplicates.

Naturally, this couldn't go on forever. While taking over the earth with copies would have had its upsides, there were many practical problems – new humans being born, the possibility of a malfunction – and so it was decided that it would be best to go after the ones who held the power and conquer the world of man swiftly and efficiently.

So the duplicates were placed at key positions, and at a certain day at a certain time the most important men in the world were killed.

Killed because once they were gone, once the invaders had the power, it wasn't necessary to mask their intentions. There were enough duplicates scattered across the globe, and they knew things, did things that nothing, no military, no scientist, could fight.

It turned out that the day Mycroft Holmes died was the day the world ended.

Sherlock would have laughed at the irony if he hadn't been busy saving as many lives as he could.

Anthea called – the last call she would ever make – and informed him that his brother was dead and that the Government was being ruled by a minister they had been suspicious of for a few months now. She barely had time to explain what she thought had happened before Sherlock heard a sound like a door was broken down.

Then a scream followed, and someone hung up the phone.

Sherlock was certain that it hadn't been Anthea, just as he was certain that he wouldn't see his brother again.

There was no time for grief, and Mycroft Holmes would have scoffed at any display of sentiment. Sherlock couldn't do anything for him, but he could try and help his friends and save the Government. He ran downstairs and called for Mrs. Hudson.

His landlady shuffled immediately out of her flat, concerned about the tone in his voice, the certain tone she had only heard a few times, one of them being him saying goodbye before he left 221B for two years.

He quickly explained to her what had taken place, that she should leave.

She refused.

"As long as England stands, you'll still have a home here – you and John and anyone who might need it. I will check on the neighbours."

He had expected her to react the way she did, and he ran out of the house, his phone pressed to his ear, going past people who had no idea what had happened, who lived their ordinary, every-day lives and didn't know that everything they knew would soon be gone unless he could do something –

As he raised his hand to call a cab, waiting for John to pick up, he looked back. Mrs. Hudson stood in the doorway, pale but determined, in her best dress (she therefore was interested in the new owner of the newsstand, he realized), looking at him, attempting to smile encouragingly.

He didn't know why he had looked back.

Finally, John's voice came over the phone and he began with, "Mycroft is dead".

Before the doctor could answer, his thoughts were pouring out of him, and he didn't blame his friend when he interrupted him with, "Sherlock, you aren't making any sense. Let me – "

He considered being selfish for a moment. It was tempting, to have John beside him for this, maybe the last fight, but the sound of a baby crying made him realize that it was impossible.

The other man cursed quietly and said, "Meredith. Tell me again, I can – "

"No" Sherlock interrupted him. "You have to get Mary and her out of London."

"And leave you alone?" John asked, sounding offended.

The consulting detective took a deep breath.

"You have other responsibilities now. You can't run after me at a time like this. The Government is being controlled by an alien". He didn't doubt Anthea's information. His brother wouldn't have believed such things possible without proof. "You have to keep your family safe. Leave."

"Sherlock..." John's voice, quiet and defeated, and Sherlock remembered, remembered long evenings and violin music and chases and laughter, and he knew this was goodbye. He didn't expect to survive. But John and his family – they could. He had been a soldier. He would take care of them. And Mary was more than capable of taking care of him.

"I will call you later" he said and hung up. It was a lie, and neither of them believed it, but he couldn't bring himself to say the words – to say "Goodbye, John" – again. Once had been enough. The doctor would do the right thing. Mary would make sure of it. Mary would take him and their daughter and run, and Mary would keep him in trouble so his leg wouldn't hurt.

He instructed the driver to get to Buckingham Palace as quickly as possible while he was texting Greg, Molly and anyone else he could think of. He chose not to call. He couldn't waste time with other goodbyes.

There was nothing to be done at Mycroft's office. He was dead; it was in the enemy's control. But if he managed to save the royal family, if there was still a symbol of the country –

People would stand up, people would –

He heard the explosion and the screams, felt the earth shake and knew Buckingham Palace was gone.

The driver had stopped and was shaking, so he left and turned towards Mycroft's office. He might as well see what had happened; maybe he could take one of them with him.

He couldn't just stand idly by and watch England fall.

He didn't even reach the office. Members of the Secret Service were closing off the block, agents who looked too clam, too unconcerned, and if Sherlock would have needed proof, this would have been it.

He didn't stay, instead he started running back to Baker Street. He had to get as many people into safety as possible, starting with Mrs. Hudson –

The house was burning.

He stood opposite of the place he'd called his home and watched as the flames consumed it. Of course the invaders would know about him. Of course they would try and find him – he'd been lucky that they hadn't spotted him at Mycroft's office. Of course they would destroy anything and anyone that made him feel safe.

Mrs. Hudson hadn't left. Mrs. Hudson was burning too. He didn't know how he knew, but it didn't matter.

England had indeed fallen on the day his landlady had left Baker Street.

He could see it, how she'd struggled against the intruders, reached for her phone; maybe they had killed her before setting the house on fire, but it was doubtful. There was no sympathy to be expected from the others.

Irrationally, he wanted to run in, wanted to see that there was indeed no hope for Mrs. Hudson. He didn't. She wouldn't have wanted it.

Someone shouted his name.

He ran. He didn't recognize the voice. It was better to run.

He didn't know where – didn't know where he could hide. He only knew that he could do nothing. He was completely powerless. Even when he'd been dead, even after Moriarty had returned, he had been able to fight. Now –

Someone ran into him. He stumbled, almost cursed. He should have paid attention instead of attempting to escape like a hunted animal.

His eyes found the ones of the man he'd run into, and recognition flashed in them.

"Raz?"

Before the young artist could reply, someone turned around the corner and stood still when he spotted Sherlock.

Stood still and didn't run into him like one would have expected. Like Sherlock had done a few moments before.

It was one of them.

Raz was staring over his shoulder. He looked terrified and young. The consulting detective mouthed "Run" before he turned around, but not quickly enough that he didn't see the other man's headshake from the corner of his eye.

Whatever stood before him wasn't human.

The man looked like any ordinary person in any ordinary city on the planet, but there was something wrong about his eyes. They lacked expression. Sherlock didn't know how to put it differently. They were empty, like glass eyes – which they probably were. Staring at the thing before him, he could only assume that they knew how to pretend to be human and that they no longer felt the need to do so. Otherwise someone would have noticed that something was wrong.

Hatred shot through him. This thing – it had killed Mycroft, it had killed Mrs. Hudson. He knew, of course, that it was highly unlikely that the one before him had committed both or even one of the crimes – no one could say how many of them were around – but this, this intruder in front of him was all he had to hate right now, all he could concentrate on.

"Do not attempt to attack me. It would be of no use".

The things' voice was flat, smooth, and Sherlock decided that he would try anyway. He knew the creature was right – but if he attacked, Raz might be able to get away. For as long as humanity still stood a chance, at least.

He was about to draw his gun when a spry can flew over his head and in the face of their opponent. He looked startled and looked down, and Sherlock fired.

The creature didn't fall down, and Sherlock fired again. And again. And again.

Finally, when his magazine was empty, the thing collapsed.

"Is it – "

Raz didn't finish the sentence.

Sherlock slowly walked over and scrutinized the thing.

At first, it looked like an ordinary human body, like the ones he'd seen at crime scenes often enough.

But then he noticed the small bits of metal inserted into the veins.

There wasn't much to see. Little pieces of copper shining through the bullet holes, making it clear that this hadn't been a human being.

He must have destroyed a circuit.

They could be killed, at least.

"Sherlock?" Raz asked. "Shouldn't we run? The body – "

The dead body was the least of their worries. If one could call it a body. Whoever was invading the country – and the earth, Sherlock guessed – could create perfect duplicates of men, who walked around and didn't cause any suspicion unless they wanted people to know what they were...

"How did you know?" he demanded. Raz was the only one who'd been running, truly running, afraid of what was going on. Others – people had been standing in front of the house on Baker Street, and the explosion of the Buckingham Palace had caused something of a panic, naturally, but there had been no screams, no attempts to flee – no one knew what was going on.

Yet.

Raz shrugged.

"When you spent a lot of time watching people, you notice some things" he replied softly. Sherlock nodded. Always spraying, always looking for policemen and passers-by who might ruin his masterpiece. He knew about people.

"You should leave" he stated.

"What will you do?" Raz asked instead of answering. Sherlock looked back down at the body. He wouldn't leave London. Not again.

He would fight.

The young man must have realized what he was thinking, because he was quiet. At least for a few precious moments.

"The tubes!" Raz exclaimed excitedly, and Sherlock raised an eyebrow.

"I beg your pardon?"

"I've seen movies, I've read books – they're going to cut off the satellites so that no one can call anyone, and stop the tubes, won't they?"

"Most likely" Sherlock said calmly. There was every reason to think that the invaders would try and cut the city – most likely the country – off from the world. If they wanted to control the people, this was the best way.

"Then we can hide in the tunnels."

Sherlock almost snorted at the thought of them hiding in a tunnel. It was the first place anyone would look once the tube didn't work anymore.

"They are long" Raz insisted. "We could keep moving".

The consulting detective considered his proposal. It wasn't much – they would be hunted down – but it gave hope. And he'd learned that people were more prepared to fight when they were hoping.

He nodded and the other man gave him a half-smile before looking down at the pavement.

"You aren't coming".

It was a statement.

"There are things I need to do" Sherlock said. He had to check on his friends. Get them out, if possible. He wouldn't risk calling. They already had surveillance over his phone and contacts, as well as every camera in the city.

Raz nodded.

"Good luck" he answered softly and turned around, and Sherlock watched him go with the strange feeling that he'd said goodbye to a friend he hadn't even known he had.

No one had come, even though several minutes had passed since the murder – or rather Sherlock shooting the imposter. People must have heard, people must have called. The fact that the police didn't come was proof that they were already controlling it as well.

Sherlock thought of Greg. The he shook himself and set out towards St. Bart's. Going to the Yard would be useless. But maybe, just maybe they hadn't reached the hospital yet.

Maybe he would find evidence that Molly had escaped. If they knew as much about him as he thought they did, they would go after all of his friends.

He quickly stole through shadows, passing people who didn't know what had happened. Trying to warn them would only cause a panic at best and make them call for help because they considered him insane at worst, so he didn't. They would find out soon enough.

He didn't make it to St. Bart's as fast as he wanted, but it appeared to be calm when he arrived. Of course, if the staff had been exchanged...

He didn't pause to think but made his way inside.

He didn't know what he had expected. Maybe Molly's body, maybe a duplicate.

But it hadn't been Molly standing in the lab, taking care of a cut above Greg's left eye with another one of the creatures dead on the floor behind them.

She immediately turned around and stared at him.

"Sherlock?" she breathed.

He nodded before he realized that he didn't know how to confirm his identity. The only possibility was hurting himself to show them there was no copper in his body, but that would hardly be efficient.

However, Greg didn't doubt him for a second.

"It's him. I know that look. He's going over his options to convince us it's him".

Molly relaxed, and Sherlock walked over to them, inspecting the cut on Greg's face and being relieved when he found that it wasn't deep.

His eyes swept over the body. It had attacked Greg with –

There was blood on its fingernails.

The only reason the DI had survived was a scalpel embedded into the thing's chest. There must be a certain connection that had to be broken, he realized; their weak point. He must have destroyed it with one of the bullets.

"I wanted to check on Molly, and suddenly this thing came through the door and attacked me."

And Molly had destroyed the creature. He'd deduced it as soon as he saw the scalpel.

The DI bit his lip.

"Sherlock – about – "

The consulting detective raised a hand to stop him. He knew that they would try to comfort him about Mycroft's death, and he couldn't allow that when they didn't know –

"Baker Street burned down. Mrs. Hudson is dead".

Molly let her hands fall from Greg's hand and the DI jumped up. Both looked stricken, and Sherlock could only assume that he had worn a similar expression when he had stood on the pavement, watching his home burn.

"John?" the pathologist asked quietly as she put a hand on Greg's shoulder a moment later to get him to sit down again.

"I told him to leave with his family" Sherlock replied. He didn't allow himself to think about it. He didn't want to calculate their chances.

"And he did?" Greg asked.

"Of course" he stated. "He wouldn't risk his family."

"No" the DI said slowly, standing up because Molly had finished treating his wound. "He wouldn't".

He was speaking carefully, and Sherlock was aware of the reason. Greg wasn't an idiot. He was the best police man in the city, and with the consulting detective's first word after having woken up from his coma and John's separation from his wife in the months that followed, plus a few things he had heard about Magnussen had led him to the right conclusion.

He hadn't understood why John had forgiven her, he still didn't. The doctor seemed to realize and only met him at crime scenes or in the pub.

When Sherlock had tried to make him see sense – in other words, assure him that Mary had saved his life in Magnussen's office – he'd stared at him and said, "She shot you".

He would never understand because he didn't want to understand, because he chose not to understand, and Sherlock had to admit that it was – nice to be thought that valuable by one person.

Greg cleared his throat.

"What will you do?"

"Fight" Sherlock said tiredly. "There isn't anything else to do."

"Do we have a chance?" Molly asked.

The DI took her hand and squeezed it briefly, and Sherlock considered it ironic that something he had expected to happen for quite some time was finally happening at what may very well be the end of the world.

"Probably not" he answered flatly. He knew he would die, it was just a matter of when. He had to get Molly and Greg out of the city, then he could fight.

He had never expected to grow old anyway.

Greg, however, was determined to make things difficult.

"We are not leaving".

Sherlock raised an eyebrow.

"Don't forget how long I've known you. You want to get us out and go against whatever this is on your own, and it's not going to happen."

Molly hadn't let go of his hand. She nodded, determined, and Sherlock realized that they must have talked about this before he entered the room.

Once he would have left them, told them to run, and not looked back. But now that he'd lived through two years of solitude and killed Magnussen and got rid of Moriarty, with their and John and Mycroft's help –

"We will need a hideout" he declared.

"Where?" was all Molly asked.

He didn't have to go into his mind palace to remember.

"The tube".

"The – " Greg's eyes widened. "Of course. Think they have shut it off yet?"

"They would be fools if they hadn't."

As it turned out, they weren't fools, and Sherlock and the others stepped into a transformed London. People were running around screaming; on their way, they passed a man who was crying about his mother who had suddenly tried to kill him.

"Should we – " Greg began. Sherlock shook his head. They couldn't draw attention by telling people about their hiding plan on the street. No matter how much they might wish to.

Greg and Molly understood and they swiftly made their way to the nearest tube station.

It was already locked down, of course, with a steel door, and several of the creatures were standing guard. They weren't armed, but they didn't need to be.

Sherlock was fascinated by how human they looked, and how well they had integrated themselves into society for an indeterminate period of time, and how they could act so alien now.

No one could doubt that they weren't human. They stood to straight, and their eyes were too empty.

"What do we do?" Greg whispered. They were hiding behind the next corner, where, as Sherlock had pointed out, there was no camera.

"We have to wait until one of them is alone. And we'll have to take him with us. If we leave the body" Sherlock hesitated a moment before pronouncing the word "they will know what we are up to. And we have to study them."

"So we wait, then we attack, somehow drag the thing with us and leave no traces that we've broken in?"

"Exactly".

Neither of them said anything.

They waited for hours, and Sherlock was beginning to despair. What if they never left a guard alone?

Around them, people were screaming and fleeing and dying, Sherlock knew. Around them, nothing was as it had been before.

Even if they tried to fight, they wouldn't be able to tell who was human and who was not. Not unless the invaders wanted them to know. And then it would be too late.

If there had been a war, it was over before it had begun.

He eyed the guards and wondered if he'd let Raz walk into his death.

Night had finally fallen, and an eerily silence over the city with it, when the guards moved.

All but one.

They probably thought they had the situation under control. They had lost Sherlock on the cameras, sure, but they couldn't doubt their eventual success.

Or so they thought.

Sherlock looked at the one remaining guard and wished he had a weapon with him. For a short moment, he thought of John, then shook himself. The doctor was safe.

He felt Greg moving behind him and a gun was pressed into his hand.

He turned around and raised an eyebrow.

"I'd rather have you armed" the DI whispered.

Molly drew two scalpels out of her coat and handed Greg one.

"Better than nothing".

Sherlock nodded at them. They knew without being told that it was time to move.

They didn't have any data on the creature before them. They were strong, and quick, judging by their experience, but when it came to their hearing or sight –

Sherlock crept as silently as possible.

Every sound his friends made seemed to reverberate in the city.

The guard didn't move. Not until it was too late.

Sherlock remembered the two bodies he'd seen. He only needed one shot this time.

The band would draw attention, but he hoped that they'd be in the tunnel by then. He still had his lock-picking tools.

He left Greg and Molly to take the body – giving the pathologist the gun so she could take care of any enforcement that might arrive – and swiftly opened the door.

Then he returned to them and helped Greg drag the body down the stairs. Molly closed the door.

For a moment they couldn't see anything. Sherlock searched his pockets for the flashlight he carried habitually.

Outside, they could hear footsteps and voices that spoke a language they didn't understand.

Sherlock didn't turn on his flashlight.

They waited again.

None of them tried the door. Either they already knew – which Sherlock doubted – or they didn't expect anyone to try and get in.

They underestimated people. It was a weakness Sherlock was familiar with.

The commotion died down after a while, and the consulting detective stole to the door and pressed his ear against it.

"Won't they see what we've done when they go through the security cameras?" Molly asked. "There was none at the corner, but there must have been one pointed at the entrance".

"We'll have to keep moving" Sherlock answered matter-of-factly, turning on the flashlight after he was convinced that everyone had left.

He handed it to Molly before helping Greg with the body.

Thankfully, the creature had been rather short and slim, and they could move rather fast.

Sherlock was going through the map of the tunnels he had in his mind palace, looking for a safe place.

The answer came quickly, and he was annoyed that he hadn't thought of it sooner.

After they had defused the bomb on the Fifth of November, Mycroft had deleted each and every map and document that could lead to the abandoned tube station. Of course people still remembered – but the others had no way of knowing about it, not if they'd come after Sherlock's return, and he decided to take the risk.

It was a long way, and they switched places regularly, Molly insisting, despite Greg's polite offer to relieve her early, that she had experience with moving bodies, and since this was absolutely true, he could say nothing against it.

Eventually, they made it, all three of them panting.

But right when he opened his mouth to tell them they were safe, at least for the time being, he saw something move in the shadows.

With three steps, he was at Molly's, who carried the gun at the moment, side and took it from her, calling, "Come out!"

The shadow moved, shouting his name.

He let the gun sink as Molly pointed the flashlight.

"Raz?"

The young man looked at him, terror in his eyes.

"Sherlock – are you – "

The consulting detective wanted to reply that he could hardly prove that, and that he might express some doubt as to the other man's identity as well, when he saw the expression on his face.

"You told me you'd go into the tunnels" he said slowly.

Raz sighed with relief and slumped down. Molly ran to him immediately, checking him for injuries.

"He's alright".

Raz laughed bitterly.

"I'd not call it that." He took a deep breath and started to tell them how he'd made it into the tube, breaking off now and then, sometimes having to pause.

Sherlock and Greg slowly came to stand in front of him and Molly.

"I – when you – after you left, I tried to find some of the others, you see – "

He meant Sherlock's homeless network. Raz had been a part of it since they'd met and was so still, although he wasn't homeless anymore.

Hadn't been homeless anymore.

"But I couldn't find Jessie, and when I – I figured Shinwell would help – "

Sherlock clenched his right hand into a fist. He was certain he knew where this was going. Shinwell Johnson was twenty years older than he and had lived on the streets since he was a teenager. He'd been the first member of his network, the best at getting information. Sherlock had trusted him.

"He was – his eyes – he'd been – replaced. But I called out when I saw his back, and he turned around and attacked me, and I ran, and somehow we ended up on the street, and a car..." his breathing grew even more panicked, and Molly put a hand on his shoulder.

"You don't have to tell us" she said softly.

He shook his head.

"No. Sherlock – Sherlock's got to know. Don't you, Sherlock?"

The consulting detective nodded. He needed all the data he could get, and talking about what had happened might do the young man good.

"So, there he lay, and – I looked for – but then people had become aware that something was happening, and others of them, of these things, they showed up and started – there was this boy, a small boy, and he was crying for his parents, and one – he – it killed him. I couldn't – I don't know how I got here. I just ran."

He was shaking and crying by this point, and Sherlock gently said, "You are safe, for now. This station – it's not on any map. Not anymore."

That seemed to calm him down a little.

"But what – what now?" he finally asked.

"We have to get more information on them" Sherlock stated, "and for that – "

"You aren't going back up there?" Greg inquired.

"We need instruments. Food. And we might bring others with us."

The DI nodded.

"You're right, of course, but..." he sighed. "Molly, are you staying with Raz?"

She was about to protest, her face pale in the dim light, but Sherlock began, "We need you here".

The young man shouldn't be left alone. And Molly knew how to take care of people.

They left with brief promises that they would return, although they knew they couldn't promise it, not really, and Molly insisted that they take the gun and the flashlight with them. Raz whimpered slightly at the thought of being left in the dark, but had calmed down enough to understand why they needed it.

"Sherlock..." Greg began as they climbed up the stairs to the nearest exit.

"About Mycroft – Mrs. Hudson – I'm sorry."

"Me too" the consulting detective replied. His brother and the DI had been friends, or at least something like it.

It was hardly a declaration of grief, but Greg understood and left him at that.

For a few moments he was silent, then he said, "John mentioned your parents once. Do you think – "

"They are most likely dead". The creatures knew about Mycroft, therefore they knew about Sherlock, and they were certainly anxious to remove any threat that might arise. And anyone connected with that threat.

It felt strange, talking about the death of people he'd spoken to not so long ago. He knew Mrs. Hudson and his brother to be dead, but it seemed utterly impossible. Against all logic, he had always expected them to be there until the end of him.

And his parents –

Sherlock was confused, the feelings clouding his judgement, and he couldn't allow that. He concentrated on the task at hand.

They made it out of the entrance – it wasn't guarded, but that wasn't a surprise, since the intruders shouldn't know about it –and to the nearest store.

Sherlock told Greg to take food, flashlights, batteries, anything he could find back to Molly and Raz while he went to St. Bart's and searched for instruments with which he could study the remains.

"No" he said before the DI opened his mouth. "It's necessary. Go to them. Wait for my return."

He paused. Eventually, he added, "If I don't make it back, get as many people into safety as possible. Try to communicate with other countries. Fight".

"Sherlock – " Greg breathed, but the consulting detective was already leaving.

Only to be stopped by a hand on his shoulder.

When he turned to ask Greg what he wanted, the DI pulled him into a hug, and this time, unlike the one after he'd come back from the dead, Sherlock reciprocated.

He left without another word.

On his way to St. Bart's, he was careful to keep out of sight. The streets were deserted, and he assumed that many people were too scared to leave their homes or had been ordered to remain there – probably while he, Greg and Molly had waited for an opportunity to get into the tunnel.

Without any incident, he got to his destination and took as many instruments that he could use as he could carry, as well as medical supplies.

On the way back, he soon found that the streets weren't as deserted as he'd thought.

He met the one man he'd believed – had made himself believe – to have escaped.

John's clothes were torn and bloody, and there was a wild expression on his face, one Sherlock had never seen before.

The doctor, whose eyes widened when he saw the consulting detective and who only managed to say his name after several attempts, didn't have to tell him what had happened.

Sherlock put down the instruments and gripped John's arm.

"I am sorry" he said slowly.

John looked at his hand, then in his face, and something like reason returned to his eyes.

"They – they attacked our car. I was driving, and I didn't manage – we had an accident. I scrambled out, but they set it on fire..."

He was shaking.

Sherlock gripped his head between his hands, as he'd done many years ago during the case John had entitled "The Blind Banker".

"John, I need you to concentrate. Please, we need to get away from here. There is somewhere we can hide".

He watched as the grieving father and husband before him transformed into a soldier on a mission.

He nodded stiffly.

"Give me some of those" he said, indicating the supplies Sherlock had put down.

He didn't think it a good idea, but didn't argue. He had to get John away from the street.

Against all odds, they made it.

The tube station was lighted by several flashlights and a lamp – which was powered by a small power unit for emergencies.

Greg shrugged his shoulders when Sherlock raised an eyebrow.

"Did you really think I wouldn't go up again?"

Sherlock didn't have an answer.

The DI saw John and for a second a smile lit his face. Then he noticed the look in the doctor's eyes, the look he had seen in countless others', at crime scenes, at funerals, and the hand he'd raised to reach out to him dropped.

"My God – " He took a deep breath and shook his head.

"John, I'm sorry."

"Oh". The sound came from Molly, who was still sitting next to Raz, who wasn't crying or trembling anymore and watching them with an indecipherable look on his face.

The pathologist looked down on the floor, a few tears rolling down her cheeks.

John didn't cry that night.

Neither did he cry on the nights that followed. Or the days.

He didn't speak of his family. He did what he was told and said precious little. Most of the time, he watched Sherlock as he tried to make sense of the creature before him.

Greg and Molly and Raz and others, others who made their way to the tube or somehow survived on the street and were found by them on their supply runs, friends and acquaintances and strangers, occasionally brought him new specimen, and forced him to eat and rest.

Sherlock was glad that they did the same to John. He tried to take care of his blogger, but he'd closed himself off and the consulting detective didn't know how to start a conversation about – losing everything. He had never been good at talks about sentiment.

John refused to speak to the others as well, though, whether he knew them or not.

Even in this first bleak month, there were positive surprises.

One of them was Mike Stamford, who managed to get into the station all by himself at their sevenths day, thinner and exhausted but determined to be as polite and cheerful as he'd always been.

There was Michael Tambson, an electrician they found in the ruins of a hotel, who was able to connect them to the few cables that hadn't been cut or were under the control of the invaders, and they found themselves in possession of better lighting and even a few heaters they'd found in a story.

There were the children they could save, sometimes with, sometimes without their parents. Sherlock had never understood the appeal of their laughter, especially not while he was working, but he did now. They reminded them with their games and their cries that they were still alive.

There was the network.

The internet didn't work, and neither could they call anyone, but an old man who hadn't left his house for years until it had been invaded and who'd got away through sheer luck, had carried an old radio with him because, as he told them, "It had served him well in the war" and some of the people, more out of pity than because they expected anything from it, made it work.

And there was one frequency where a human soul could be heard.

Sherlock didn't have to wait to give the man who was talking about survivors in Dartmoor a name.

Henry Knight was alive, and he was trying to contact others.

It took days, but they were successful, and slowly, other voices joined theirs, voices from other cities, other scared humans who'd found together and were trying to survive.

The creatures had conquered England, that much was clear, but they couldn't contact other countries. It was more than likely that they had control over the whole planet.

But there were other people out there, and the survivors in the tube station held on to that thought, held on to the voices, cheered when new numbers came in that said a group had grown and cried when one group stopped responding and they knew what had happened.

It gave them pain, but it gave them also hope.

Paradoxically enough, John's silence led to have Sherlock more interactions with the others than he could have predicted. All the survivors knew who he and John were – it wasn't surprising, considering the media coverage of his death and return – and it was soon know among them who the doctor had lost. They kept their respectful distance from him, let him grieve the way he chose to, and Sherlock was surprised at their tact.

At the same time, they seemed to cling to Sherlock. Maybe they expected him to make everything right, maybe they were simply fascinated by his work – but they all came to talk to him, ask his advice, tell him about the supply runs.

A young girl, seven years old, called Maddie, who'd been found wandering in the streets, had developed a strong affection for him and kept coming into the small tunnel he used for his experiments every day, chattering about how Greg had taken her up and how she'd got the last of the white bread but had given to a younger boy and demanded that he tell her what he was doing and that he really shouldn't work that much because her mother had always said that one shouldn't be forced to work all day.

Sherlock liked her. Her visits didn't annoy him, which would have surprised him a few short months ago.

He caught himself at the thought that she was what Meredith would have been like if she'd survived.

He wondered if John knew her or if he ignored children as best as he could, these days.

Now and then, Sherlock went out and got supplies, but mostly, he stayed in the tube station and worked.

But even he needed breaks, and he liked to take them when most were asleep. He wandered around, looked at the survivors, talked to his friends; Raz, who had decided to make their living space more cheerful and was spraying every wall he could find; Greg, who coordinated the supply runs; Molly, who worked with John in their so-called "sick bay".

"Do you think this is how it'll end?" Raz asked him once, finishing another wall. This one depicted a starry night, because he'd decided that the children in their group should see what life could be like.

"Hiding in the underground?" he added.

He didn't sound bitter or angry, only curious, and Sherlock thought it might have something to do with the fact that the young man had found true acceptance for once in his life. There were no homeless, or former homeless, among those who'd lost their homes.

"I don't know" he answered honestly, and Raz turned around.

He said quietly, "You'll think of something. You always do."

The trust in his voice caused Sherlock to return to his work immediately.

And finally – after long hours of work, almost half a year after the day that changed everything – Sherlock gleaned some information from the specimen.

It took months. But he did make progress.

The bodies of the creatures didn't decompose, which helped greatly. Sherlock was able to make out that there was indeed a vital part of their circuit hidden in their breast, albeit small, and that it had to be hit precisely in the middle to stop functioning. Sherlock and Greg and Molly had got lucky.

The discovery that their eyes glowed silver under ultraviolet light was helpful in many ways. Now they could make sure that all the members of their group were human, they could tell Henry Knight and the others, and they could check after every supply run that no one had been replaced.

The intruders had a hard disk as well, and after several attempts, Sherlock finally extracted one without destroying it in the process, and eventually they procured enough instruments to read it. It took almost two months, and the consulting detective came close to giving up on a few occasions, but then he looked at John and knew he had to continue.

And finally, it worked.

Naturally, it wasn't in any language they could understand, but he was Sherlock Holmes. He'd taught himself French as a child, and although he had nothing to go one, he would succeed because he had to.

During one of the many nights (or days, it was difficult to distinguish them in the tube station) Greg came to sit beside him. It wasn't unusual, but that he'd stood in the entrance for some time before fully entering his tunnel was.

He watched Sherlock's progress for a while, not saying anything.

Finally he began with, "John is sleeping".

"Good" the consulting detective answered. Although they didn't speak much, except about supply runs and the invaders, he had noticed John's pale face, the shadows under his eyes and that he was growing thinner every day. They all were, naturally, but the doctor more so than the others.

"I – " Greg cleared his throat.

"Does he talk to you?"

Sherlock understood it as "about his family" and shook his head.

"He chooses to cope on his own. I respect that".

"Are you sure he is coping?"

Sherlock didn't know. "Coping" meant many things, and he could tell that John was functioning, at least. Beyond that –

He didn't know what to do. He didn't know how to break the silence.

Greg patted his shoulder as he stood up.

"He'll talk eventually" he said and left Sherlock with an encouraging smile.

A few days or nights later, it was John who came to sit beside him.

"How is it going?"

"Slowly" Sherlock answered frustrated before remembering who he was talking to. He turned his head, but John was smiling, a small but real smile, the first one since Sherlock had found him.

"But you're making progress".

"Yes" he confirmed.

"Good. That's – " John cleared his throat. "You're too thin. You should eat more".

He hadn't told him that in a long time.

Sherlock put away the hard disk he was working on.

"And – while we're at it – you're pale. You should get out more. Mike was right".

Of course. Mike Stamford, who had spent some times in learning the names and stories of every survivor and introducing them to each other, who had introduced Sherlock and John, would try to get the doctor to talk to him.

"This is important" Sherlock stated.

"Not as important as your health".

He couldn't say when he'd gripped the hard disk again. He still had to crack the language of the intruders. If anything, he'd have thought that John would welcome his attempts to decode the material as swiftly as possible. John had lost so much. John wanted answers.

The doctor's hand reached out and loosened his fingers. He put the hard disk on the table and said, "It's a beautiful night. Let's take a walk".

Sherlock didn't comment on the insanity of doing so in their situation.

On their way, they passed Mike Stamford. Sherlock gave him an almost imperceptible nod, which he answered with a small smile.

The night was calm; the stars were easy to see now that most of the lights were turned off at sunset.

Sherlock and John walked through the city that had once been their home, the consulting detective making certain that they weren't caught on any security cameras.

London had changed greatly. He still knew the streets, but houses were burned down or ransacked, they were silent, too silent, and the constant chatter of human noise had been wiped out.

Sherlock only realized where he'd been leading them when they stood in front of St. Bart's. He cursed whatever subconscious association had made him chose this way, and was about to turn around, when he saw John's face in the dim light of the stars.

He was staring up at the roof.

Several emotions passed through his face before he looked down again, and when he spoke, he sounded defeated.

"They are gone".

"I know" Sherlock answered. There was nothing else to say.

"I – " he took a deep breath. "I should have – "

"There was nothing you could have done" Sherlock interrupted him. It was true. It was a miracle John had made it out alive. They had been determined to kill anyone connected to the consulting detective. If anything, it was Sherlock's fault.

"That doesn't make it easier" John looked at him.

Sherlock nodded. He knew it didn't.

"I couldn't – I – " John broke off and shook his head. "It doesn't matter what I thought".

He'd most likely blamed Sherlock, at least for a short while. It was a natural human response, and while the consulting detective admitted that it hurt, he understood.

"So – what do you have?" John asked, changing the subject.

Sherlock told him what he knew about the invaders, there in the front of St. Bart's.

And when they returned, John insisted on helping him decode the language.

"I picked up a few things during my tours..."

It wasn't a good argument to convince Sherlock, but John was talking again, and he agreed gladly.

On the first anniversary of Mycroft's death, the old man with the radio, Garrideb, died. He hadn't spoken much, but he asked for Sherlock on his deathbed, and the consulting detective stood up immediately when Molly called.

"I read about you. And I watched the telly. You can do it. You can save them. Promise".

Sherlock did. If the man chose to believe in him and it gave him comfort in his last moments, he was more than ready to.

A month later, he finally cracked the strange language.

For a few hours, he and John were alone with the information, the story.

A people on a dying planet. Logical and cold, ready to take Earth as their own, a signal travelling light years, picking up enough information to build the replicates, then transferring their conscious into it, the first members of the army arriving a year before the day England fell. Infiltrating the lives of the people of the Earth, preparing their takeover, then slaughtering those who stood in the way.

But what gave Sherlock hope was the last part of the story.

There was a General. Their hieratical structure appea4red to be very strict, and if they managed to take down this one replicate –

It would be easy to kill the others. Logical and highly intelligent – but obedient and dependant on orders.

They had to destroy the General.

He was sitting not in the ruin of Buckingham Palace, but in Mycroft's former office, and Sherlock's hands clenched into fists as he translated it. John squeezed his shoulder briefly.

The General never left the office apparently. They didn't need to sleep or eat as long as their conscious mind was stuck in the replicas. Their real bodies were far away, on their home planet.

When Sherlock read the General's plan, he couldn't believe it.

Just like Moriarty, he was convinced that Sherlock would come to him.

It made sense, sense when one had read the newspaper articles and files on Sherlock Holmes.

They did know much about humanity, but little about human nature.

But it gave Sherlock a chance.

He could get in. He could kill him.

Of course only at the cost of his own life. But it was a fair price to pay.

He didn't tell his friends, instead choosing to reveal to them his plan of building a bomb that would destroy the General's replica as well as any others that might be in the vicinity.

He didn't mention that he'd be the one to trigger it, right in front of the General. He would only get one chance. He couldn't risk simply pushing a button and waiting for an explosion.

So, on the day when he finished the bomb and explained that he'd plant it that night, he knew that this was goodbye. And they didn't.

Or so he thought.

John cornered him as he put the bomb carefully in a bag.

"When are we going?"

"You are not coming".

"Then you are not going".

The stubborn expression on John's face told him that he wouldn't be able to convince him otherwise, but he had to try.

"John, your life doesn't have to be – "

"No" he said, raising a hand. "No, Sherlock. This isn't about – them" his voice trembled slightly. "They are gone. I have accepted that. I do not wish to die. But this – this is about the world. And you. I won't let you do this alone."

After a pause, he added, "You and me. To the end".

It was the first and only time in his life Sherlock ever initiated a hug.

A small group was standing near the entrance; Greg and Molly hand in hand, Mike with tears in his eyes, Raz looking down on the floor, and Maddie.

Sherlock shot Molly a look. Maddie should be in bed by now.

But then she hugged his legs and he picked her up and she said sadly, "Goodbye, Sherlock" and he understood that she knew, with the strange instinct that was peculiar to children, what would happen.

He squeezed her and put her down.

He came to stand in front of his friends, John beside him.

He didn't hesitate as he shook Mike's hand, kissed Molly's cheek, or patted Raz's shoulder.

He also didn't hesitate to hug Greg back.

"Take care of them" he said quietly, so only the DI could hear. "Afterwards, it will be easier – let others know. And don't forget you still have to save the world."

"Don't worry" Greg answered just as quietly, his voice shaking a bit.

John said his goodbyes, brief but heartfelt, and they left for the last time.

They met no one. Despite not keeping themselves away from the surveillance cameras, no one was coming for them.

The General was waiting.

The door wasn't even locked.

Other replicas were standing on the stairs, looking at them but not moving. John stayed close at his side.

Sherlock had prepared himself – he had been sure what the General's replica would look like.

But he still found it difficult to look in his brother's face.

"Sherlock Holmes" the General said calmly, "You are a difficult man to find".

"I try to be" he replied, putting the bag down. Once, there would have been banter. Once, he would have found this fascinating.

But as John had put it this was about the world. They would save Earth. They would save London.

They would save their friends and so many others.

"You will not be able to hide it and cause it to explode later" the creature said. "You wouldn't get out".

"We're not planning to" Sherlock said simply. He turned to John and smiled.

John smiled back.

To the end.

Sherlock pressed the remote he'd kept in his coat. In the small part of a second before the bomb detonated, looking at John, seeing him truly smile for the first time in over a year, he could imagine, could see in front of him how Greg and Molly and Mike and Raz and Henry Knight and other people, humans, took back what was theirs. How the world was saved.

He knew their sacrifice was worth it.

The explosion could be heard over miles.

Author's note: This is longer than I expected. I tried to build up the story and crate suspense, and it just grew from there.

I hope you liked it, please review.