"You've come alone, I trust?" An American accent. Interesting. Sherlock crossed the threshold at the top of the stairs, hands clasped behind his back. He'd realized on the way over that he'd forgotten the revolver on the table by John's chair, but it didn't matter, there was no time to fetch it if he were to reach the building in time.

"Of course." He muttered incredulously, eyes darting about the room as he absorbed all the detail. The walls were decorated with the runic markings and patterns he'd become so familiar with over these last months, each sigil and symbol and seal placed rather haphazardly across the walls. A quick glance upwards revealed more on the ceiling.

Movement in the shadow beside him drew his attention away from the markings as the man he was addressing emerged. He didn't seem very intimidating. He was a slim, short, dark haired man. He carried himself with authority. His smart suit said businessman, or something of the sort.

Sherlock's concentration was broken as he spoke.

"Well, well. Here we are, Sherlock Holmes, in the flesh." He drew the last syllables out theatrically.

Sherlock rolled his eyes.

"If you're aiming for intimidation you may as well save yourself the effort." He turned to face him correctly, watching the man slide his hands into his pockets, smiling smugly. His eyes flicked back up to the man's, narrowing slightly in annoyance.

"So I take it you liked my work?"

Sherlock's lips twitched up into a cocky smile.

"It was entertaining for a while. Sadistic, yes, but then, what murder isn't considered sadistic? The first two were a bit of a challenge; you're very good at cleaning up after yourself, you didn't leave much to go on. But the third, well…" He trailed off, fixing the man with a patronizing frown.

"You practically left me a picture ID. Hair, fingerprints, bite marks. But not yours. They all belonged to a corpse, dead four months prior to the murders. That would be considered strange if I didn't know what I was dealing with. So tell me, then, what the point of all this is? Have you simply gone on a killing spree in order to meet me 'in the flesh'?" He raised his fingers in air quotation marks as he mocked the man's words. "What could you possibly want with me?"

The man simply smiled in return.

"I do have a website, you know, with my cellphone number on it. You could've just texted me and saved yourself the trouble."

"My higher ups would like to offer you a chance to change the world, Mr. Holmes. I was sent to offer you a proper invitation. They told me to get your attention by any means necessary, and I couldn't resist the temptation to have a little fun while I was at it." He reached into his jacket and pulled out a simple business card. He extended his hand but didn't move any closer. Sherlock scoffed, reaching out to snatch it from him.

"Change the world, indeed." He muttered half to himself, glancing over the card. It had a phone number on it, nothing more.

"Are you going to give me a name?"

"Where's the fun in that? I'd rather let you figure it out." Sherlock tossed the card down at the man's feet and put on a cheerful smile.

"Tell your superiors my answer is no. Now if that's that, then, well, good morning." He added as he turned to leave.

"You don't have a choice." He paused by the doorway that lead to the stairs, sighing exasperatedly. He turned only his head to look at him.

"Don't I? There are perks to being a consulting detective, you know; I get to choose my own clients."

The man shook his head, a chuckle rumbling in his chest. Sherlock felt his nape prickle, both in irritation at being laughed at and something else, something more sinister that he couldn't quite put his finger on. Suddenly he was uncomfortable, he wanted to leave. He put on another dramatically fake smile and squared his shoulders.

"Well, this has been pleasant, and while I'd love to stay and chat, to be quite honest I've got much better things to do. And I've already declined, so, as I said before, good morning. Oh, and I've already called in a police escort for you, they ought to be here any minute, so don't bother trying to leave-"

"You're too deeply involved, Sherlock. You possess something very important to us. We'd like it back." That shut him up. He set his jaw as the object in question flashed through his mind.

"I've no idea what you're talking about."

"Don't be cute. I haven't got the time. Now, you can either enter our employment by your own choice, or we'll take you by force. The latter situation could get messy, for you and your friends." Sherlock's sea-green eyes narrowed dangerously, fingers curling into fists behind his back.

"I haven't got any friends. You've nothing to threaten me with." The man's self-satisfied smirk was making him nauseous. He imagined all the different ways he could make him stop smirking, most of which involved his fists or a blunt object of some sort.

"Haven't you?" He gestured to the shadowed room immediately behind Sherlock, smirk widening into a grin. Sherlock threw a glance over his shoulder, and as he did the man snapped his fingers.

Sherlock's mouth dropped open but nothing came out.

A light flickered on to reveal a small office space, complete with broken table, overturned filing cabinets, and a single bare bulb that flickered annoyingly. In the middle of the ruined room sat John, bound to a chair. Blood dripped from his forehead, nose and swollen cheekbones, evidence of an apparent beating. His head hung limp, chin on his chest.

"If you don't join us willingly, we'll force you to. It won't take much, really, knowing you. We just thought we'd give you a choice."

"You don't know me." He turned to face him again, fists aching to pummel the nameless man that just stood there, smiling at him.

"Why have you involved John in this? He's nothing to do with this, he doesn't know anything."

"Doesn't matter what he knows or doesn't know. He's leverage, Mr. Holmes. Look at you. Look at how emotional the great, stoic, sociopathic consulting detective gets when his favorite plaything is threatened."

"He's not a thing." Sherlock's voice was venomous. "Let him go. I don't have what you're looking for."

"Of course not, you burnt it. But you've memorized it. We know you have, that's how your mind works; when you find something that sparks your interest you obsess over it. You absorb it and learn all there is to know about it. The book is in your head, Mr. Holmes. That's why we need you."

John stirred, drawing Sherlock's attention. He gave a muffled groan as he opened his eyes, blinking at the flickering light.

"Let him go and I'll give it to you."

"That's not good enough. The spells in the book only work for the possessor, and since you were the last to possess it, well.." He trailed off, shrugging his shoulders. "Doesn't leave you much choice, I'm afraid. Either you agree to work for us or I kill him and take you anyway."

Sherlock narrowed his eyes at the man, observing and absorbing every detail, trying frantically to find a breaking point, a weakness, anything. Suddenly a though occurred that restored his confidence completely.

"I assume by "take me" you mean to have me possessed, am I correct?" The man's eyebrows raised a fraction of an inch.

"Good, I was hoping you'd catch on sooner or later." Sherlock smirked.

"You can't, or you already would have." The man's confidence deflated a bit, his face draining to a sallow yellow color.

"If I wanted to possess you, you'd be possessed." He spat. He blinked, eyes flashing black for a moment before returning to their normal color.

"I was giving you a choice."

"Rubbish." The sound of car doors slamming outside signaled the arrival of Lestrade and his troops. If he was going to do it, it had to be now.

"I must say, I'm a bit disappointed in myself. I should have known earlier that you aren't human. I'll need to further educate myself on your kind, find out what makes you tick-"

"Sherlock? is that a demon? What-" John interrupted himself with another groan as he came back to full consciousness, eyes bouncing between the man and the demon staring at him.

"It's alright, John, I've got it handled." He was done playing with this demon. It was time to send it back where it came from.

He took a deep breath and began to chant one of the exorcisms he'd memorized from the book.

"Crux sancta sit mihi lux, non draco sit mihi dux-" The man was laughing at first, his head tipping back, but then he gave a pained howl and dropped to his knees, choking. When he looked up his eyes were wet black, mouth dripping charcoal colored smoke. Sherlock felt a sick twist in his stomach but he forced himself to continue, "-Vade retro satana, nunquam suade mihi-"

More screaming sounded from behind him. Without stopping the chant Sherlock turned in time to see a spattering of bright red stripes bloom in the middle of John's jumper as a demon that hadn't been there before tore into him with an archaic looking blade. Even through its own suffering it found the strength to rip open John's stomach. Sherlock didn't have time to react as the demon smiled, twisting the blade as he wrenched it upwards into John's chest, black eyes grinning. "-Sunt mala quae libas, ipse venena bibas!"

Two pillars of black smoke filled the room, spewing forth from their host's bodies with a terrible sound, wind racing through the small room. They circled in the air for a moment before disappearing into the floor, leaving behind burning circles in the old, decrepit wood. Together the bodies dropped to the floor; they remained there, motionless. Dead.

It hadn't lasted more than a minute.

Sherlock turned, breathing hectic as he saw John. He was on the floor now, still tied to the chair, blood seeping through his jumper and dripping from his mouth. His eyes found Sherlock's. They were wide and pained and utterly horrified.

Sherlock fell to his knees on the floor beside him, shoving the corpse of the demon away. His fingers shook as he snatched up its blade, freeing John from the chair.

"John-"

"Sh- Sherlock-" He was choking, blood pooling around them from the gaping wounds in his stomach and chest. Sherlock had his jumper balled up in his fists, pulling John to his lap in a frenzied mess of movement. His fingers were slick and red and shaking. For the first time in his life, he didn't know what to do.

"John, I-"

John's hand found his, fingers curling over his blood-slicked wrist, the other gripping his shirt with what little strength he had left.

"Sherlock, it's okay. It's alright-" His voice was weak, trembling.

"Stop talking, you're wasting your energy, just- just hold on, John. Try to keep breathing." He couldn't think of anything else to say. Someone kicked a door open and footsteps topped the stairs. Lestrade was the first to find them. When asked what had happened, Sherlock could only yell at him to get a bloody ambulance here immediately before turning back to John.

"It's alright," John was saying, blood running down his cheeks now as he coughed, teeth stained the gory color of death. Commands were being barked, a search for more suspects being conducted. Sherlock was deaf to all the commotion, all of his energy focused on John.

"You did all you could, it's okay-"

"No, no it isn't! How is this alright?" Shame burned his throat as emotion rose. He was Sherlock Holmes; he didn't get flustered, he wasn't supposed to have emotions. And he most certainly wasn't supposed to be comforted by his friend as he died.

None of this was okay.

"John, I'm so sorry, I shouldn't have- this wasn't supposed to happen, I- he came out of nowhere-" His voice shook, words coming in a rush. He felt like a child, trying to explain an accident that wasn't his fault. He closed his eyes, leaning his forehead against John's.

"John, hold on. I'll get you out of here, I'll- I'll get you to the hospital. You'll be okay, John, you'll see, just hold on!" 'Don't leave, John. Don't leave me here alone.' A child's voice pleaded in his head.

John's mouth worked to form words but he had no strength left to speak. His hand fell from Sherlock's as his last breath escaped his lips.

It had all started six months earlier. The case had seemed cut and dry, or at least cut and dry as murders go.

There had been two victims at the first scene, both young women, mid-twenties, good job, happily married. Seemingly everything to live for. The only apparent ties they had to each other was the church they attended. Sherlock had found little to no evidence of the killer.

The women had been found in an abandoned saw mill after having been reported missing three days earlier. A boy and his sister had found them while playing a game of hide and seek. The women had been hung from the ceiling and exsanguinated, all major arteries cut. The room they were in had several bizarre symbols painted on the walls, door, ceiling and floor. Research revealed them to be Enochian sigils. It was decided that a satanic cult was behind the killings, though no evidence had been found with which to accuse or question anyone. All they had were the symbols and the corpses.

Sherlock, of course, was intrigued. John, however, was not.

"What do you mean, 'rubbish'? This is by far the best Christmas I've had in a very long time, John."

"People are dead, Sherlock, murdered, without evidence left behind. How does that not bother you?" He'd said from behind his chair, arms crossed over his chest. "Even you, Sherlock, couldn't find any evidence. Not only is that an unprecedented event in itself, it's creepy, and I don't want anything else to do with it. And Christmas was two weeks ago, this doesn't count." Sherlock had shrugged him off and gone back to his research.

It wasn't until the fourth body that John got truly fed up. Sherlock had dragged him along as he always did, despite the man's plans to go to dinner with the nice woman he'd met at the shop a few days earlier. The scene was, for intents and purposes, the same as the first. Only this time there was evidence, lots of evidence, almost as if it had been left there on purpose. And something else. A book.

After it had been examined and all the prints they could find had been lifted from it, Sherlock convinced Lestrade to let him have it. He pored over it for the next few weeks, researching everything about it, memorizing it, trying to find others like it.

One night John came home late from the surgery to find Sherlock sitting cross-legged in front of the fireplace. The book was sitting open in the middle of the burning logs, pages curling as they blackened and turned to dust.

John wasn't going to say anything, he'd told himself as he watched Sherlock watch the book burn. But he couldn't help himself.

"Sherlock, you alright?"

"Demons, John." The doctor frowned, eyes closing for a brief moment as he made sure he'd heard the man correctly.

"Demons?" Sherlock had a slightly harried look about him when he turned to look over his shoulder at his flat mate. His hair was disheveled, his eyes were wide. It was all too reminiscent of the Baskerville case. John was worried to say the least.

"How long has it been since you've slept, Sherlock? Look at you, you're a right mess-"

"I just got off the phone with Lestrade. The DNA I found at the case came back positive. It belonged to a Geoffrey Balgow, 36, missing for four weeks and two days. His body was found today in the sewer by a construction worker investigating a blockage." The consulting detective took a sip from a glass of amber liquid, one that John hadn't noticed previously.

"He's been dead for four months, John."

John's frown had deepened, and he'd shaken his head.

"That doesn't make any sense. In fact, none of that adds up, how could-"

"Possession, John. The man was possessed." John didn't believe him, and he had no qualms in speaking his mind about that fact. The argument hadn't lasted long. John was tired and hadn't wanted to hear anymore. He'd excused himself and gone to bed, leaving Sherlock to his drinking.

The next day was Sunday. When John woke and came down to fix breakfast, Sherlock wasn't home. He didn't return until late that evening. Neither of them spoke a word to each other, merely nodded 'hello' and continued about their own business. There had been tension between them ever since.

Then Sherlock received a letter. It had an address on it, and a note:

"3 o'clock this afternoon. Come alone. It's time we met face to face."

Sherlock found it on his way out. He'd planned on going to the morgue; Molly had a few corpses for him, and he had a few experiments he'd been saving, but this was much more interesting than anything he could have come up with.

John had been at the hospital when Sherlock found the letter. He hadn't let him know where he was going.

He hadn't wanted to be involved. And now he was lying in a pool of his own blood.