A week passed, dragging its feet like a grumpy teenager. John spent his time in his chair, reading or researching. He memorised all the fairytales, just in case, but the rest of the time was slow, almost agonisingly so. There was nothing to do, no one to see. Just the flat, and Sherlock, who was going slightly insane.

He slept the first night, but the other six days he was up, mumbling and stretching out on the sofa like a cat. He took naps -half hour bites of recharging - but that was it. Microscopes littered the table; the mirror had been examined this way and that; the hair had been screened for so many different toxins John doubted Sherlock had even remembered the names of them; the scrape of dirt on the floor had been burned, frozen, dissolved in acid, filtered and dripped into a horrible looking steel contraption. None of it was working, and it was tearing Sherlock apart.

"John," he said, exactly seven days from when Lestrade had wandered in, "I can't get this to work."

John glanced up from his paper and looked Sherlock in the eye. "I can't help you."

Sherlock let out an odd moaning noise and bent down, his chin tickling the arm of the chair. "You can, John. Please. Just take a look at what I have."

Sighing, John stood up and wandered to the kitchen table. It was drowning in paper and plastic bags, covered in pens and scribbling. John was slightly amused to see that Sherlock had resorted to writing on his own hands, black marks like tallies covering his skinny wrists. "Ok, what do want me to look at?"

"Everything."

John rolled his eyes. "Ok." He parted a pile of papers and stared at himself, the image fractured in the mirror shard. Picking it up, he weighed it, feeling its density. It had been coated in a fine blue material that was rubbing off in his hands. "Hmmm. Right." John grabbed a random bottle of green liquid from the table and dabbed some onto the mirror. Nothing happened...not that he was expecting anything to. "Well...that proves...something."

"It proves that water with pH indicator in it does nothing to glass, like every primary pupil knows."

John swallowed a retort and picked up another bottle. Behind him, Sherlock sniffed, and John could just tell he was raising his eyebrows and cocking his head in fake interest. John pretended he didn't care and unscrewing the cap, let a tiny drop of the fluorescent blue water fall onto the mirror. There was a sizzle as it reacted with the powder and then, words scrawled across the glass, jagged and painted in drooping lines.

John almost dropped the bottle on the floor and Sherlock simply stared at it, his face the picture of shock and surprise. Within moments, he was calm again, composed, and, tugging the mirror from John's hands, started to read aloud its message;

"Open the door, my princess dear,

Open the door to thy true love here..."

Sherlock glanced at John, who was still staring, open mouthed and incredulous at the magic that had just unfolded. "Well done, John. I think we may have found the next clue. Only an idiot would have thought to put potassium permanganate onto copper sulphate...the killer must know I have an accomplice...or his researcher of course..."

Sherlock continued rambling, spreading his thoughts into the air like paint on a canvas, but John wasn't listening. He didn't even register Sherlock's insult. Instead, he was thinking, his mind caught in a rush of ideas and questions and answers and references. Vaguely, he wondered if this was what Sherlock felt all the time - this stampede of processes and decisions and books and words. No wonder he went mad sometimes.

"...and, of course, this could mean anything, any fairytale...John? Any ideas?"

John blinked and hurtled back into the world of the living and the sane. "Eh," he said, glancing at the words again. He had the story on the tip of his tongue, just bursting to escape. "The...Fr-The Frog Prince! He - the frog, I mean- says it to the princess every time they meet."

Sherlock nodded and with careful, traced steps, he placed the mirror back on the table and walked to the sofa. He promptly lay upside down on it, his feet touching the wall and his mop of hair washing the floor. John had found this position in particular quite disturbing when he had first arrived, but now...well, it was just Sherlock's way of thinking.

"The Frog Prince..." he muttered, his eyes fluttering shut. "Is that the one that takes place in a pond?"

"Yes, but also a castle."

"Too many options. The clue isn't in the setting then, it must be in the story itself. Were any of the characters given names?"

"No," John replied. "I don't think so." He longed to have the laptop in front of him, instead of having to this by memory, but it was through in the other room, and he wasn't leaving, not when Sherlock was deducing.

Sherlock's brow furrowed. "Were there any key items in the story?"

John thought for a moment. "Well, the pond, the golden ball-"

Sherlock sat upright, his stomach muscles tightening through his shirt. His eyes snapped open and he stared fixedly at John, his round eyes sizzling with passion and curiosity. "Golden ball?"

"Eh, yes? At the start of the story, the princess drops a golden ball into the pond. That's how she meets the frog."

"Right...right..." Sherlock's eyes closed and he muttered for a few seconds, his hand waving in the air slightly as he thought. A miniature mind palace - one he could access quickly and with distractions in the background. In this case, it was most likely to be a map, judging by the way his hands were moving in straight lines. But what he was looking for, John didn't know. As far as he was aware, there wasn't a place called Golden Ball in London.

After about half an hour, Sherlock's eyes opened and he quickly stood up and grabbed his coat. He yanked it on, winding his scarf around his neck at the same time. John started forward. "What? Where are you going?"

"Where are we going, John. Plural. I know where the next victim is." He tugged the scarf until it was tight around his neck and then grabbed his phone from the table. Pressing a few buttons, he glanced at John. "Well, come on."

John jumped into action and grabbed his coat, shrugging it on effortlessly. The last few days had been warmer, but not warm enough to walk around without a jacket. Not for the first time in his life, John wondered what it was like to live in America and not have your life dominated by the weather.

Sherlock swung the door open, his eyes still glued to his phone. John hurried out of it and started to walk down the stairs. Sherlock joined him and as they marched out into the hall, Sherlock held up his hand and thrust his phone into John's face. "YANA Inc Warehouse, in the industrial estate. It stored Christmas decorations, mainly golden baubles."

"Ok. Well, are we going?"

"Yes. Don't bother getting a cab, it's a few minutes' walk."

Nodding, John opened the door and walked onto the icy pavement. Immediately, he turned left - two months of living with a walking Sat-Nav had increased his sense of direction, and now he was more or less sure of where he was going. Sure enough, Sherlock didn't correct him, and they walked off down the road together.

People passed, chattering on their phones and carrying heavy bags of shopping. They were all so...oblivious. So blind and naive. They didn't know about the murders, about the deaths that were going on behind closed doors. They didn't know who the tall man with the trench was, and they didn't know he had been a lifeless lump of flesh a week ago. They didn't know the soldier walking beside him, metal, sharp and deadly, buried deep into his leg and scraped out with blunt tools. These were the same people that didn't notice the missing Rapunzel, who didn't care about death or life, so long as they weren't locked in the middle of the struggle between them.

John considered this, and found himself thinking they were lucky. They were so fortunate to not have to put with genius-level tantrums and painful legs that spasmed and jerked at odd moments. They were so fortunate not to know the secrets that swamped this dark and dangerous city, the ones that hid in shadows and crept in alleyways, always hiding their ugly scarred faces. They were so fortunate, so blind.

And yet John would never give it up. The battleground was exciting, interesting, and Sherlock, as much he wanted to kill him, was his best friend, his roommate and his colleague. The leg was a wound, yes, but it was one he had sustained honourably, and it reminded him of courage and strength when the world was imploding, crumpling in on itself.

The battlefield was bloody, and the casualties kept rising, but he would rather be a general than a mindless drone below.

"Left."

John's feet, following the sound of Sherlock's voice, carried them into a dark and twisted lane, covered in cobbles and broken bits of glass. The lane curved and folded in on itself, the bright light outside lost in shadows of the towering houses on either side. Sherlock, unaffected, kept walking, his head up, his eyes darting, and his cheekbones rouged by the wind.

"Right."

He turned into a tiny side-street and increased his pace, his long legs sliding over the iced cobbles with ease.

"How much further?" John asked, slipping over a patch of black ice.

"Not much. One left turn and we're there." Flashing a rare smile, Sherlock started walking again, taking a sharp turn down another alley. Then a shaft of light pierced the darkness and the blue sky opened up like a book. John stepped into the light and saw the warehouse. It was a grey with patches of dull red where the metal covering had rusted. It looked a bit evil, but warehouses always did in his opinion. However, there was something wrong.

John watched as Sherlock strode towards it, confident and blissfully unaware that anything was wrong. John stayed rooted to the spot and after a few moments, Sherlock turned around. "Yes?"

"Do you not think..." John paused and wondered how to continue. In his head the problem had seemed so obvious, but now it seemed stupid. "Well, the other places were a bit more...magical. This doesn't look like a fairytale setting."

Sherlock's face was smoothed out, a slate of blank incomprehension. "Your point?"

"Well, you said the killer was methodical. Choosing two beautiful places and then a dark one doesn't seem very methodical..." John trailed off. God, he sounded stupid.

Turning around, Sherlock started walking again. "Crime scenes are never beautiful, John, unless you're me. Now, hurry up."

John sighed and hurried forward. He thought he had something - the place was different somehow, even if he couldn't completely put it into words. It wasn't as magical, as sparkling as the forest and the tower; instead it was dull and dark and menacing. There was something else as well. It didn't seem as...completed. There was something missing. But, Sherlock was the boss and John wasn't in any position to argue. He wasn't letting Sherlock walk in there alone.

Joining Sherlock, John walked towards the warehouse, twisting his path towards the entrance. It was gaping and black, and shivers crawled up John's spine. He longed to stop, to order Sherlock to stay, but he couldn't. Sherlock was the boss. Sherlock was always the boss.

The darkness swallowed them whole as they stepped into the empty metal beast. Nothing. No noise; no light; no scent. Just blandness, darkness, silence. John turned to Sherlock. "Did you bring a-"

There was a sharp pain in his neck and then nothing became everything