Author's note: So, on with the story.

I don't own anything, please review.

John swallowed. He hadn't expected this. W he didn't like Mycroft – was sure he'd never be able to trust him – he knew that he was dedicated to his country, would never do anything that would harm its safety. In fact, it was probably Mycroft who had kept it safe and sound over the last two decades. He wouldn't –

But if he was really possessed by a demon –

He still didn't believe it. But just the possibility was enough. Mycroft had always had much, perhaps too much power, and it didn't matter if he was possessed – what mattered was that Anthea was convinced he was trying to take over the control of the whole country, that he wanted to kill every member of the Government –

"What about the Queen?" he suddenly asked, stupidly. He hadn't meant to; but he remembered Mycroft's comment about an "old friend" quite well, and it was difficult to believe that the man who could enter Buckingham Palace whenever he pleased would readily murder the royal family.

Anthea glared at him in a very Holmes-like way.

"Do you really think he would spare the royal family, despite them having little to no legislative power?"

John shook his head. Anthea had never raised her voice; she had never been impolite; she had never looked scared. She was convinced something was wrong with Mycroft, and maybe he wasn't possessed – alright, John still thought it impossible – but if Sherlock and Anthea and Greg all thought that he wasn't himself, they had to be right. They knew Mycroft best.

"Can you put holy water into his tea?" Sherlock calmly interrupted the silence. After a moment, Anthea nodded.

"It shouldn't be too difficult. He only ever allows me to make his tea anymore – officially because he's scared of poison. Unofficially..."

She shuddered and John understood why she had called the Winchesters and Castiel to begin with. Mycroft had never shown any interest in – that kind of thing; in fact John thought both brothers were asexual.

"He likes to see me" she finished, determined not to say anything else, and John was relieved that at least Mycroft hadn't done anything he would regret once he got back to normal.

Yet.

"Perhaps – " he started, unsure, but she interrupted him.

"I can take care of myself, thank you. And I barely have time to serve him the tea anyway."

John wasn't reassured but realized he wouldn't get any other answer, so he asked, "You will make his tea with holy water? How does it work, exactly?"

"I have to bless it with a rosary" she answered. "I know how it works."

For a moment John considered asking her how she knew, but he doubted she'd answer. So he just nodded and let Sherlock take the lead.

"You have to do it soon" the consulting detective announced, "otherwise – "

"Trust me, Sherlock, I know the consequences" she replied drily. Both Sherlock and John knew that she wasn't angry, though. She was just run down and scared and wanted this to be over.

Like they all did.

"Text me once as soon as you have the results" Sherlock said before bidding Anthea goodbye and leaving without another word. John followed him as always. Most people would have considered his last remark heartless, but John knew the consulting detective better than that; Sherlock was always more comfortable to do experiments than work with people, and to see his brother's test as such helped him deal with it.

They took a cab back to Baker Street.

Sherlock took his burn phone out to send a text, and John inquired, "You are texting – "

"The Winchesters, of course, to be specific, Dean".

"I would have thought you would be more comfortable texting Sam" John answered; the younger Winchester had certainly seemed the more professional of the two.

"Dean will suffice" Sherlock replied as if it explained everything; the doctor was so used to such answers that he didn't even ask him to elaborate but instead was content to look out the window for the rest of the journey.

Sherlock did the same, his mind racing. He had known something was wrong with his brother, but locking off the country like a villain in these James Bond movies John loved to watch? That just wasn't something Mycroft would do. He had always preferred to pull the strings in the background; even if he became, for lack of a better word, "evil", he would not try to install himself as the dictator of England. He would maybe kill the Government, the royal family, Sherlock could understand that; but he wouldn't plan to let the public know that it was he who had done all this. And according to Anthea he was certainly going to be the country's new leader. Why else would he make sure the army obeyed his every command?

Sherlock had to admit that it almost seemed like Mycroft truly was... possessed.

He was reasonably sure that he could rule out a mental illness. He certainly knew none which symptoms would fit his brother's behaviour, and if John did, he would have said something. He could easily renounce the idea that Mycroft had always been like this and was only now starting to put a long-laid plan into motion; he had known him all his life, had looked into his eyes when he'd talked to him about his addiction, his career choice, John; Mycroft was not a sociopath. Mycroft would never plot to take over the country (although his doctor might have claimed, and not without justification, that he already had – but sometimes it wasn't the goal that mattered, but the way in which one reached it, and this wasn't Mycroft's style, it was as simple as that).

Once again, Sherlock remembered his favourite saying.

Once you eliminate the impossible, whatever remains, however improbable, must be the truth.

And while he couldn't say for sure that his brother was possessed by a demon, he couldn't rule it out, either. It was improbable – in fact he could hardly think of anything more improbable – but it wasn't impossible.

But he was getting ahead of himself. They had to wait for the result of the test.

Strangely, Sherlock didn't know which outcome he feared more.

Because, should Mycroft be possessed, they would somehow have to vanquish a demon with the help of three Americans they knew nothing about.

And yet, if he wasn't –

Sherlock would have to prevent his brother from taking over the country. And he knew Mycroft.

Foiling his plan and putting him into prison wouldn't be enough.

He would have to kill his brother.

"Sherlock" John interrupted his thoughts. He turned his head to find the doctor staring at his hands. He looked down on his lap and realized that he'd clenched them into fists. He forced himself to relax and asked, casually, "Yes, John?"

He shook his head. "Sherlock, please. I know you are worried."

"I don't think "worried" is the right word". Sherlock looked out the window again and bit his lip.

John understood.

"Be careful what you wish for?" he quietly inquired.

Sherlock nodded.

John didn't know what to say. Going up against Mycroft wouldn't be an easy task. And furthermore – no matter if there was a demon inside him; he had to be stopped; once and for all.

And that meant.

John quickly squeezed Sherlock's shoulder, let his hand drop and said, "It'll all be fine".

They both knew it probably wouldn't, but his words helped anyway; Sherlock gave him a half-smile before looking out of the window again.

John cleared his throat.

"So when do you think" he asked "will Anthea send us the result?"

"Knowing her, she will want to know as soon as possible. Mycroft usually drinks tea after meetings. It shouldn't be long".

They didn't speak again until they reached Baker Street.

Sherlock immediately went upstairs, ignoring Mrs. Hudson who came out of her flat to see her boys and ask what was going on; a moment later, music started drifting through 221B, and John knew he most likely wouldn't talk until Anthea texted him.

"It's alright, Mrs. Hudson, he is just – been having a hard day" he said, trying to convey to his landlady without words that they couldn't talk because this had to do with Mycroft.

Once again, he decided that most people didn't give Mrs. Hudson the credit she deserved; her eyes lit up with understanding immediately and flitted over to the umbrella stand near the door that Mycroft never used but which she associated with him for obvious reasons.

John gave an almost imperceptible nod and she smiled, patted his shoulder and wished him "Good Luck" before returning to her flat.

John smiled to himself as he went up the stairs. Talking to Mrs. Hudson, even if he couldn't say anything, always made him feel better.

He went into the kitchen to make tea; Sherlock needed to be alone with his thoughts for a while. All they could do was wait. Wait for confirmation that demons existed and that Mycroft was possessed and that they had to tie down the British Government somewhere and perform an exorcism, or Mycroft wasn't possessed and they still had to bring down the British Government.

He understood why Sherlock didn't know which answer he'd prefer. He didn't either. He put Sherlock's cup on the table next to him – the consulting detective let it grow cold, but John didn't care – and sat down.

They didn't have to wait long. As Sherlock had predicted, Mycroft apparently took tea after the meeting.

When the text alert rang out Sherlock carefully put the violin on the table and read it silently. A strange mixture of relief and disappointment flashed over his features before he told John what it said.

Just two words.

No reaction.

John swallowed. He hadn't realized until this moment what it would mean for Sherlock if the test was negative. He had known, of course, that they would have to bring down Mycroft either way; but he hadn't realized to himself that it meant –

It meant that Sherlock's brother was a criminal and now indeed the most dangerous man he had ever met.

"I am going to let the Winchesters know" Sherlock announced, his voice eerily calm. But John knew him too well. He saw the tension in his body, the stiff movements of his fingers as he typed the words.

"Sherlock..." he started, unsure of how to proceed, but the consulting detective shook his head.

"It doesn't matter".

"Yes it does" John argued. "You can't pretend this isn't – "

"I always told you he was my arch enemy" Sherlock replied, unable to keep the bitterness out of his voice. He laughed a short, hollow laugh and John didn't know what to say.

Sherlock got an answer to his text and frowned.

"They want to meet us".

"Why?"

"Dean apparently doesn't think it necessary to give us details".

John would have laughed if the situation hadn't been so grave. And here he'd thought Sherlock was the master of leaving people in the dark.

"Where – "

"Mycroft is in his office; afterwards he'll go to the Diogenes Club. And anyway, even if he knew we met the Winchesters, it wouldn't matter now. Demon hunters are not going to help us bring him down". Sherlock sighed and looked down at the floor.

"But I told them to meet us in the warehouse where we met Anthea earlier anyway".

They quickly made their back to the warehouse. Sherlock didn't say anything during the cab drive, and John decided to let him in peace. At least for the time being.

The Winchesters and Castiel were waiting for them.

"What do you want?" Sherlock asked, letting a bit of the frustration he felt seep into his voice. "The test was negative".

"Yes it was" Sam answered. "But as far as Anthea told us, your brother is strong, right?"

Sherlock nodded. "He is. He is the British Government. But I don't understand – "

"Some people, special people, can fight against demons, exercise some control over their body even if they are possessed" Castiel answered. "If your brother is one of them, but has been acting strange and unlike himself anyway, there is a chance that he is possessed by a very powerful demon. And these have been known not to be affected by hold water".

"What then?" John demanded, "Another test?"

"Yes" Dean replied gruffly. "But you won't like what you hear."

Sherlock inclined his head to make him understand that he was listening.

"Even if they aren't much affected by it, rock salt hurts them like a bitch. We have to shoot your brother".

Author's note: I figured any demon able to possess Mycroft would be strong enough not to react to holy water. Also, don't worry, I know where this is going, and it's going there. Eventually.

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