Author's note: On with the story – something is happening. Finally.

Warning for angst.

I don't own anything, please review.

Mycroft – or rather Moriarty – smiled, the smile Sherlock had known when the consulting criminal had still been human, and it was all the proof he needed to know he was right.

Once you have ruled out the impossible, whatever remains, however improbably, must be the truth.

He knew Moriarty was dead. He'd thought demons didn't exist.

And now he was standing in front of his brother who had been possessed by the consulting criminal for God knew how long.

Sherlock had noticed the change in Mycroft a while ago, but he didn't know whether Moriarty hadn't been able to fool him. Maybe he's been there for a while now, and simply chose to show Sherlock that something was wrong when he got bored; maybe he's been around ever since he shot himself at the roof of St. Bart's.

Moriarty – despite his enormous intellect, it was difficult to admit to himself that it was him and not his brother he was talking to – sighed.

"You still think too much, Sherlock. Why does everything have to be so complicated? I came back not so long ago. I think you noticed it right away, but hey, nobody's perfect, right? And anyway – if you didn't, I would have been bored".

His eyes turned back, were Mycroft's eyes once again, and Sherlock was surprised at the urge to shoot him. He couldn't. The hunters had said they could exorcise the demon, no matter how powerful it was.

Then again, Moriarty probably knew everything about exorcisms, and Castiel had informed him that Mycroft would die if the demon had hurt him fatally during or after the possession. Knowing Jim, this was more than likely. Hurting Mycroft meant hurting Sherlock either way – whether he managed to exorcise him or not.

Moriarty had always known how to wound him.

I will burn the heart out of you.

He still could. If Mycroft was indeed wounded fatally – and it was more than likely – Moriarty could leave his body any minute and possess John or Mrs. Hudson or Greg. He could go on until there was no one left. He could destroy Sherlock completely.

"Sherlock, don't be so obvious" Moriarty whined. "If I'd known you'd become so caring in the time I was away, I wouldn't have fought my way out of hell to begin with ". He paused a moment. "All right, maybe I would have. This is hell we're talking about. But still – I think you could show a bit more enthusiasm. I was the only one who ever really distracted you after all."

Sherlock was just about to answer – although he didn't really know what, since he was mostly concerned with keeping John safe – when Sam started to speak.

It was obviously some sort of exorcism in Latin, and Sherlock listened, intending to commit the words to memory, when Moriarty waved his – Mycroft's – hand and everyone except the consulting detective was pinned to the nearest wall.

"Hunters. You are all so – predictable. One of the reasons I went for Sherlock. He might have disappointed me at our last encounter, but what I heard afterwards..."

Jim's eyes glistened.

"There are quite a lot people in Hell who would like to have a little chat with you, my dear. And why shouldn't they? You send them there. You are just like me after all. Like I said before: We are the same. And now you are not even on the side of the angels anymore. You killed. You killed without a second thought, and for purely selfish reason. "I want to get back to my friends", what kind of justification for murder is that? When I heard what you had become I realized I had to go back; I realized life wasn't as boring anymore as when I left it."

Sherlock swallowed. He knew there was no point in turning around; Moriarty wouldn't make the mistake of letting John or his other companions even move an inch.

He hadn't expected to ever see Moriarty again – nor to hear him state out loud what he thought about himself, in the dark hours before dawn when John was sleeping and not even his violin could keep the memories of what he'd done in his three years spent dead away. He hadn't talked to anyone about them, simply courtly informed his friends that he had dismantled Moriarty's web.

But the consulting criminal was right.

He had killed forty-seven people in these three years, and he remembered every single one of them. He'd even tortured a few to get the information he needed, and it was what haunted him the most: the blood slowly dripping unto a concrete floor, the cries, the radio playing some song at full volume so no one would hear his victim scream.

He had indeed changed. How well he remembered what Moriarty had said to him on the roof of St. Bart's long ago.

Thank you.

Just two words – two words which most of humanity wouldn't pay much attention too, which Sherlock hadn't thought, or tried not to think, about while he had done what he had had to do. Because it was obvious what Moriarty had meant.

He had known that Sherlock would become a killer, a torturer, a criminal; he had known that he had unleashed a new danger upon the World. And he had been so sure of it that he had killed himself.

He had killed himself because he'd known this was what Sherlock would become. He had killed himself because he had known what he had unleashed; because he had known the choice Sherlock would make. Even if he hadn't foreseen that Sherlock would cheat Death, he had hoped he would. He had hoped he would become a vigilante. A man who killed without a second thought.

And the one conclusion Sherlock could draw, the one he chose to keep locked away in his mind palace, was a simple one.

In the end, Moriarty had one.

And he had known it. He had known that he'd won the moment he shot himself, he had known that he would win either way, whether Sherlock would kill himself or turn into a murderer.

"At first I thought I'd possess John" Moriarty continued pleasantly, "but then I realized that, if going for power – why shouldn't I go all the way up? Plus me and Mycroft have a history. What can I say? I'm a sentimental man."

Sherlock heard John struggle to say something behind him. Moriarty grinned.

"Still the faithful pet, I see. Anyway, where was I? Oh yes, dear old big brother. I have to say, Sherlock, he is quite the fighter. He keeps trying to regain control over his body."

Naturally Mycroft would fight. He wouldn't stop fighting. And Sherlock didn't know whether Moriarty had a way of killing him. Maybe he was lying, and Mycroft was long gone.

"Where would be the fun in that? Having Mycroft fight a useless fight is so much more entertaining".

Could demons read thoughts? If they did Moriarty surely wouldn't tell him.

Sherlock's mind was racing. He had to get the others out of the house somehow. He couldn't allow anyone to die because the consulting criminal was still as obsessed with him in death as he had been in his lifetime.

"I can only assume" he started calmly, "that your plan goes further than to simply rule the country".

"And why is that?"

"Because once you do you will be bored".

Moriarty chuckled. Sherlock still couldn't get used to hearing the consulting criminal's words spoken in Mycroft's voice.

"You are right. So what do you think my plan is?"

"Obvious" Sherlock stated. "Chaos. You will open the prison doors, crash the economy, abolish every law in existence. You will have your own private Hell to play in."

Mycroft's eyes turned black again.

"Oh no, Sherlock, not Hell. Trust me, no one wants to go back to Hell once he's been there. Not even me. Don't worry, you'll see why – eventually".

If he had wanted to shock or scare Sherlock, he hadn't succeeded. If there was a Hell then the consulting detective had known for a long time that he would end up there eventually.

"We've gotten pensive, I see". Moriarty tilted his head, obviously intent on continuing the conversation, and Sherlock had had enough.

"What do you want?" he asked.

"Can't I just have a chat with an old friend?"

Sherlock didn't answer and the other man shook his head.

"You really have changed. But, to answer your question – I just wanted to make sure all the players know the rules."

"The rules?"

"You don't think I would kill you when I've only just found you again? I want to play, Sherlock. And it's going to be so much more fun than the last time".

Sherlock had had enough of Moriarty's games, but if it meant they got out of here for the time being...

"Fine".

Moriarty grinned. "I knew you wouldn't disappoint me. Oh, and" he waved his hand and Sherlock heard a thud and what could only be a suppressed groan of pain from John. He turned around to find his doctor's face contorted.

"Don't look like this, it's just a concussion and a dislocated shoulder. For now".

Sherlock looked back at the consulting criminal. He was waving cheerily at him.

"Anyway, until later, my friends!"

In the next moment he was gone and Sherlock's companions slipped down from the walls.

He was at John's side in an instant. The doctor's gaze was unfocused.

"Sherlock? Was – "

"Yes, John, but we can talk about it later. Can you stand?"

"I think you".

Sherlock helped John up and asked "Where did he go?"

"Where he wanted" Dean answered, picking up his gun. "I am surprised he did, though. He could easily have killed us off."

"It's not his style."

"Who is he?" Sam asked.

Sherlock tightened his grip around John as his friend started to sway.

"I will explain everything, but first we have to get John home."

"Won't he – " Dean inquired, but Sherlock interrupted him.

"He won't. I know him. He wants to play. We are safe for tonight".

Sam and Dean looked sceptical, but Castiel nodded and moved to help Sherlock with John.

When Dean saw his friend take John's other arm, he nodded too and slung his bag over his shoulders.

They slowly made their way out of the house and eventually caught a cab a few streets from the mansion.

Author's note: Sorry for the shorter chapter.

Moriarty as a demon – I didn't think I would love writing it so much.

I hope you liked it, please review.