I'm so sorry guys! I can't believe it's taken me four days to upload this chapter! I've just been so busy lately with exams and stuff, I promise to warn you in the future if I'm gonna be late with an update, and I promise wholeheartedly that I will not give up on this story, so don't worry :) here you go, exciting stuff coming up!

John

What was with this bloody headache?

I gripped my head again, but when it went off again after a few seconds I was relieved to see that Sherlock had not spotted the action. He was too busy staring at the body and occasionally rattling off deductions that my foggy brain couldn't possibly hope to follow, let alone understand. These bursts of pain had been happening frequently in the ten minutes we'd been standing in this cold, damp warehouse, and I'd lost count after the fourth one. All I knew for certain is they seemed to get worse every time, and though they never lasted more than a few seconds at most, they also seemed to be getting longer as well. It really wasn't the most convenient of timings, as Lestrade and the other members of the police force kept giving me funny looks whenever I scrunched my face up in pain, and Donovan had even gone so far as to ask if I was alright. I had been surprised at the genuine concern she'd shown, and had been about to thank her for her sympathy when Sherlock, being Sherlock, had interrupted and told her that she was distracting his important deductions. Needless to say, she hasn't taken it very well, and had stormed off to the other side of the room, muttering obscenities. I had given the detective a hard look when I caught him smirking after her, though he didn't react other than to continue with his dizzying conclusions. At least, they were dizzying for me.

I could tell Sherlock was enjoying himself, and I really didn't want to interrupt him mid-stride, which is why I didn't enlighten him to the frequency of the waves of agony rolling through my head every minute or so. It was obvious that no one else was going to comment either, knowing full well the consequences of interrupting the consulting detective.

Only when another wave forced a small whimper out of my lips did he finally stop talking long enough to look at me. By the time he had managed to take in my agonised look and shift his own features into a look of concern, the pain had fled and I no longer had to clutch my forehead. I gave him a small smile to show I was ok, but as I'd expected he didn't drop the issue as I'd have liked him to. He continued to watch me in his calculating way, and this had led to the rest of the Yard officers doing the same.

"John-" he began, but I cut him off, not wishing to make a scene, and I knew that this case was more important than whatever was going on with me.

"I'm alright," I said, my face still holding a forced smile that Sherlock obviously wasn't buying for a second. "I just need some air, I'll be back in a couple of minutes." I didn't wait for him to answer, and instead turned swiftly round and walked out of the building. I could feel his penetrating gaze watching me as I walked, so I made sure to look relaxed and confident, even though I was silently panicking. I had never in all my years heard of something like this happening, and I was a doctor! Then again, until a few weeks ago I hadn't thought it possible to swap bodies with someone, and look how that turned out.

The thought stopped me in my tracks. Thankfully I was not in sight of Sherlock or anyone else when I had stopped or they might have come over to see what was wrong. I had to lean against the wall of the warehouse as my brain frantically went through conclusion after conclusion, none of them looking the least bit good. I hadn't really thought about any possible side effects of the machine, but now that the thought had burrowed its way into my brain it refused to leave. What if it had damaged me? It had obviously been a work-in-progress, and I'd been the first test subject, so there was no way of knowing what it could have done to my brain. Another thought made my breath hitch in my throat. What if the machine had given me a brain tumour, or had messed with my memories? Could I still do everything that I used to be able to? Oh God. What if I was dying?

This thought triggered another splitting headache, and I cried out from both pain and fear, though I smiled grimly when I realised that whatever I had coming to me, Moriarty almost certainly would have to endure too. I really hoped he was enduring these agonising headaches, and I wished I could see his face if he was. When this particular episode had finished I slid down the wall to the uncomfortable concrete floor and just sat there, mildly panting. I hoped Sherlock would come for me soon, as there was no telling how long I had left if I was in fact going to die from the after effects of the machine, and I wanted to tell him how he kept me sane. Not just through the events of the past weeks, but since the day he'd found me. I had been thoroughly bored with life since wing discharged from the army, but that day had changed everything. I realised that I'd never properly thanked him for that, and decided that if I made it through the next few minutes I would make sure he knew how much I appreciated his help.

That happy thought sent me back into the white hot pain that seemed to be making an appearance every thirty seconds or so now, and I clenched my fists so hard I'm quite sure my fingernails drew blood from my palms. I heard footsteps round the corner of the warehouse to the side I had collapsed in, and then Sherlock was kneeling next to me, repeating my name over and over like a mantra. I finally surfaced from the pain long enough to ask him not to leave me, and to start telling him about my own deductions of what was probably happening, but he shushed me.

"Call an ambulance!" He barked behind him, but my eyes were shut so I didn't see who he was shouting at. "It'll be alright, John. I'm here, you're going to be okay." I could tell he said it as much for his benefit as my own, but it made me feel instantly better. I relaxed slightly against the wall, and as the pain gripped my whole body this time I didn't try to fight it, and instead gave in, letting it flow through me like my life-blood. All I knew was pain, and the pain was everything.

Then, I woke up.

"Damn." I said.