Sherlock glanced up disinterestedly as John let three figures into their flat. Not clients. Bored, he looked back down at the slides under the microscope, but paused as he ran the men back through his mind. Something was... off about them. Slowly, trying to remain relatively unnoticed, Sherlock looked back up at them. All three were obviously American, just arrived, but why they had come all the way to London, he couldn't tell yet, especially as the one in the leather jacket appeared to be still on edge, likely scared of flying. His brother, the tall one, was obviously well-read and had gone to university, from the way he was scanning Sherlock's bookshelf. They had both grown up without their mother, but the shorter, and likely older, one did have an amulet of some kind that he was attached to. Possibly from his brother. They were obviously very close and had been living together for some time now, and from how he was standing, the older one was fiercely protective of his brother.

But the third figure was different. He wasn't related to the other two, not by blood anyway. Sherlock now realized that the aura of strangeness came from him. He seemed to not quite fit in or to perfectly obey the rules of etiquette. Actually, the more Sherlock watched him, the more he reminded Sherlock of himself. He was quite intelligent, though not in the same ways as Sherlock was. He was quite fond of the trench coat he wore, and obviously loved the one in the leather jacket, though the other seemed to either not be aware of that fact or did not reciprocate the feelings. Strangely, there was a distinct lack of personal or identifying items that he wore, but -

"Hello, Sherlock, was it?" the leather-clad man said as he approached the kitchen and pulled out a badge. "I'm Detective Simmons, and these are my colleagues, Detectives Frehley and Bonham. We're with the FBI and we'd -"

"Nope."

"Excuse me?" 'Detective Simmons' said, taken aback.

"Those aren't your names. And FBI? With that hair?" Sherlock said, looking at the other brother. He scoffed.

'Detective Simmons' cleared his throat. "The - uh, the regulations have changed. New management and all that."

"Still not your names." Sherlock looked up to see an incredulous look on the other man's face. "You want me to believe you share names with members of one of the most famous rock bands in history and just happen to be working together? And the fact that you're obviously brothers, not the trench coat one, the other two, means you should share a last name. If you're going to have an alias, at least make it believable." He glanced over at John, who was looking at him with disbelief. "What?"

"You... You listen to KISS?"

"No, of course not," Sherlock said, a little too quickly. He looked back down at his microscope. "It's useful to know common aliases."

Still slightly unsettled, 'Detective Simmons' turned to look at his brother, with a question in his eyes. His brother shrugged, and the older one sighed. "Fine. I'm Dean Winchester and this is my younger brother Sam. We're here because we... Uh, we think someone you know might be a demon."

Sherlock's head snapped up to look at him. "You what?"

At this, Sam stepped in. "What he's saying is, we've been monitoring all the signs of demon activity in the US and UK and all over. Long story, don't ask. Anyway, all the signs were there - well, here. We don't know what they're doing here, but -"

"Demons."

"Yes..." Sam said cautiously, wondering what the detective's reaction would be.

"You two are idiots. Demons don't exist. I'd expect better from someone who went to uni." Sam and Dean exchanged a look. Sherlock ignored them and continued. "What's your name?" he asked the third man.

"Ca-"

"Calvin," Sam interrupted. "He's a buddy of ours."

John cleared his throat before Sherlock could get in a snarky comment. "Sherlock? A minute?" Quickly, he pulled Sherlock into the hallway and closed the door. "Sherlock, what if they're telling the truth?"

"They're not. Demons, angels, all that supernatural nonsense, it's ridiculous. It's all hoaxes and illusions. They're obviously delusional and obsessed and should be sent away for the safety and sanity of all involved."

"Ok, so say there's not actually demons. There's still something going on, otherwise they wouldn't have come all the way from America. I say we hear them out and see if there's something we can do to help, or at least make them think we did something."

Sherlock looked at his flatmate for a second, then went back into the room and sat in his armchair. John quickly followed suit. "Sit," Sherlock said, indicating the couch. Sam and Dean obeyed, but 'Calvin' stayed standing, saying that he wasn't tired, despite the time change. "What makes you think there are 'demons' here?"

The brothers looked at each other. "Well, we've sort of grown up in this business, you know? We know the signs," Sam said.

"What business is that?" John asked.

Dean spoke. "Saving people. Huntin-"

"We hear about dangerous creatures and... other things that most people don't know about," Sam interrupted, "and we kill them."

"What sort of 'creatures'?" John said, skeptical.

Dean cleared his throat, wary of how Sherlock had reacted a few minutes ago. "Well, uh, werewolves, vampires, ghosts, shape shifters, -" Sherlock scoffed. "-a lot of other things, and... demons."

"Right... So, how would we know if there was a demon here?"

"Well, the best way to tell if one has been around recently is sulfur. Have either of you smelled any sulfur recently? Even just the tiniest bit?"

John thought for a moment. "Well, there was something a few days ago that I suppose smelled a touch like sulfur."

"I was experimenting with carbon dioxide and yogurt. Something went wrong."

"Ah... Sorry, I guess you won't be able to get any leads through sulfur, with Sherlock experimenting non-stop. He tends to do that when-"

"Shh!" Sherlock suddenly cut him off. "What's that noise?"

"What noi-"

"SHH! Listen..." Soon, John realized he could hear it, too, a sort of mechanical wheezing that seemed to come from downstairs. After a few seconds, it seemed to stop, and a few more seconds after that, voices and footsteps on the stairs. "It seems we have visitors." Sherlock glanced at the brothers. "More visitors."

The room was silent as the door opened to let in a short woman with brown hair, obviously an elementary school teacher who loved kids, but had none of her own, and was unmarried with a romantic interest. As Sherlock kept observing her to see what else he could find out, a tall, lanky man in his fifties strode into the room, pointing a small device that glowed at one end at everybody in the room. Sherlock shifted his attention. He, like 'Calvin', was, for some reason, a bit difficult to glean any information from. It was almost like he was-

"Not human." The strange man had stopped in front of 'Calvin'. "You're not human."

"Dammit," Dean muttered. "Sammy, I told you we shouldn't have let him come."

"You think we could have stopped him?" Sam hissed back.

"What are you...?" The older man said to himself, still scanning 'Calvin' with his pointer, which was making a strange buzzing sound. He suddenly stopped and held it up to his face to look at something on it. "No. No, that can't be! It must be broken. I knew I should have upgraded it. That can't be right."

"Dean, he's going to find out eventually, so we might as well just tell him and save him the trouble."

"But-" He tried to come up with a good argument. "Fine. You do it."

"Doctor," Sam started. The grey-haired man looked up. "Your screwdriver isn't malfunctioning. That's Cas. Castiel. We told you about him, remember?"

"Ah, yes, and you couldn't have been bothered to mention that he's a bloody angel?!"

"WHOA, hold on, a what?" John interrupted. "A-an angel? As in, heaven? God's warriors? Gabriel and Lucifer and that whole lot?"

Finally, Castiel spoke. "Yes. They are my brothers. Along with Michael, Uriel, Ezekiel, Balthazar, Raphael-"

Dean cut him off. "Yeah, Cas, thanks, I think we get the picture."

Sherlock, who had been sitting quietly in his chair observing, abruptly stood up and without a word walked to his room, closing the door behind him. The room fell silent, watching him. After a moment, John stood up as well. "Excuse me," he said. "I'll... I'll go talk to him."

John opened the door to see Sherlock curled up on his bed with his house coat draped around him, not moving. "Go away, John."

"I know this is extremely weird and doesn't make a lot of sense, but maybe if we just hear them out and see what their explanations are, then-"

"No." Sherlock stood up. "Don't you see what this is? They're trying to make a fool of me. Make me look like I'm the same sort of gullible idiot who falls for these things. 'Sherlock Holmes Believes in Angels! You Should, Too!' or 'This just in: Greatest detective in England couldn't see practical joke was a hoax!'"

"Sherlock. Didn't you see them? The taller one, Sam? He looked smart; you said yourself he went to uni. The old man and the girl who came in, they both looked intelligent, though the older one seemed a touch mad. And Castiel seems smart. Why would they trick you? What possible reason would they have? Half of them aren't even British! Why could they want to humiliate you?"

"Because they always do."

"Who always do?"

"People like them." And with that, Sherlock wrapped his house coat back around him and flopped onto his bed, the conversation clearly over.

Sighing, John walked back into the living room. "Sorry, he's a bit reluctant to talk right now. He'll be fine. Just... give him a little while. He's not used to stuff like this, all the supernatural creatures and such." He paused and turned to the older man and the young woman. "Sorry, what did you say your names were? Doctor, right? Doctor... who?"

"No, just the Doctor, thanks."

"Oh... Ok. And you are...?"

"Clara. Clara Oswald. And you? Military man I can see. Sorry, the Doctor didn't tell me much about who we were meeting, just that if I liked mysteries as much as I liked meeting Robin Hood, I'd be very happy. He didn't say anything about demons either or angels or anything and I don't even really know who these other people are, just their names, and I'm so sorry, I just keep talking and never know when to shut up when I'm nervous."

John smiled. "John Watson, former captain, 5th Northumberland Fusiliers. Was a doctor, but got shot and shipped off home. Very nice to meet you. These are Dean and Sam Winchester. They apparently hunt demons and vampires and such. And the one who just stormed out of here, that was Sherlock Holmes."

Clara's smile froze on her face. "Sherlock. Holmes. The Sherlock Holmes? As in 'The Hound of the Baskervilles' Sherlock Holmes?"

"Yes, I believe that's what I titled one of our cases. Just don't let Sherlock know you're a fan. He's not always very grateful for that sort of thing."

"Oh, ah, no of course not!"

At that moment, the door to Sherlock's room banged open, and the man walked out, heading straight for his chair, where he promptly sat down. "Tell me about this demon you're hunting."