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John settled at the table with a cup of tea. As Saturday mornings with Sherlock went, it had been a quiet one, but he didn't mind. All the better to catch up on the blog, write up some new cases. He glanced over at Sherlock, who was staring at a small object held between his fingers.

"What is that?"

Sherlock looked up. "A French decathlete found completely out of his mind, surrounded by one thousand, eight hundred and twelve matchboxes – all empty except this one."

"And what’s in that one?"

"The inexplicable."

He slid the cover of the matchbox open and it emitted an otherworldy yellowish glow. A genuine smile spread across Sherlock's face, the sort that usually accompanied the discovery of human body parts or the revelation that a serial killer was on the loose. John stood and crossed the room for a closer look, but the box appeared to be empty except for the astonishingly bright light.

"That's quite a trick. How does it work?"

"No idea." Sherlock tilted the box to get a better view inside.

"Fiber optics, has to be."

"I thought so at first, but I haven't been able to detect anything other than paper in the interior. Whoever made this did a fantastic job of concealing the power source as well."

They both stared at the light for a long moment.

"So you said the man – the decathlete – went mad."


John waited for him to elaborate, but Sherlock continued to stare at the light instead, apparently transfixed. "Sherlock?" John put his hand on Sherlock's shoulder. "Maybe we shouldn't—"

There was a strange sensation right behind his navel, something that was immediately alarming and unidentifiable, and then darkness pressed in all around.


John groaned, disoriented. Awareness began to seep back in: He was sitting in a chair and his head was pounding. Must've fallen, hit his head on something, and Sherlock had helped him into this chair. It wasn't his chair: the cushion felt all wrong and the light coming in through the window was at the wrong angle; he could tell even through his closed eyelids. Sherlock's chair then. Which meant Sherlock had seen him pass out, had probably lugged him off the floor and into this chair.

John opened his eyes and winced at the brightness of the daylight. "Oh, hell. Sherlock?"

There was no answer. Perhaps he'd gone down to get help? The pain in John's head flared again, and he lifted his hand, pressed his fingers against the spot where he assumed he'd hit it on the floor. No way to know which direction he'd fallen; backwards seemed unlikely, given the position he'd been in. The fact that he was leaning forward at the time seemed to indicate that—

Hair. He touched his head again, combed his fingers into hair that was not his, that was much longer and finer, that tangled around his fingertips. He gave it a tug, and yes: it was definitely attached to his scalp. He frowned: he must've hit his head harder than he'd thought.

There was a sharp intake of breath from his left, and he turned his head to see a person on the floor pushing himself up to sitting. John's eyes refused to focus for a moment, but even through the fuzz, it didn't seem to be Sherlock. His attacker, perhaps? Multiple escape strategies flitted through his mind and he clenched the arms of the chair, prepared to stand.

His eyes suddenly focused, and he nearly shouted at the sight before him. That was… him, sitting on the floor. He closed his eyes and opened them again, but the scene didn't change: He, John, was sitting in this chair and looking at himself – who was staring back at him with a look of horror on his face.

"What's going on?" The voice that came out of him, that rumbled in his ears, was distinctly not his own.

"I don't know," the John on the floor said, and then appeared to have the same revelation about his own voice. He looked down at his hands and his body and went very, very pale.

"Sherlock?" John called, and the John on the floor looked up at him, forehead creased.


"Oh, no. No no no." John shook his head and stood, suddenly filled with manic energy. "This is not possible, it's… whoa." Vertigo. The room looked completely different than it had before, shifted, as if he were… taller. Much taller. He reached out to put a hand on the back of the chair, and had to try twice, because it was several inches lower than he'd expected. He looked down.

That was not his hand, nor was it his arm, or his clothing. With a desperately sinking feeling, he turned to look at his reflection in the mirror above the fireplace.

Sherlock's face stared right back at him.

"Bloody hell." The words looked incredibly bizarre coming out of Sherlock's mouth, but yes, there was no denying that he was, somehow, against all explanation or logic… Sherlock. Behind him, Sherlock – apparently – clambered to his feet and stared at his own reflection, slack-jawed. John's eyes met his in the mirror. "What do we do?"

"I have no idea." Sherlock crossed to stand next to him and went up on his toes. "This is completely unexpected."

"Unexpected? Is that the best you can do? Christ, Sherlock, look at us! What the hell is going on?"

"There is no logical explanation, but yet, here we are." Sherlock – and God, it was hard to call him that when all John could see was his own face – squinted at himself in the mirror. "I had no idea you were so short."

John gave him an incredulous look. "We're standing here in each other's bodies, and that's what you're thinking about?"

Sherlock ran his fingers through John's short hair, ruffling it a bit. "Or that you look so old." He made a face in the mirror.

John made a sound of frustration and turned away. He felt incredibly wound up, so much so that he was compelled to move, to pace, to bounce on the balls of his feet. "What the hell was in that matchbox?"

Sherlock turned and scanned the floor around them. "Yes, that's as good a starting point as any. Let's see, where might it have— Aha, here it is." Sherlock reached under the sofa table and came up with the matchbox in his hand.

"Right, of course. We might be able to reverse the… whatever it was. We should recreate the exact moment."

"Yes, I think so. Precisely as we were."

"But which way? Bodies, or…?" John gestured between them.

"Or what?"

"I don't know. Souls?"

Sherlock's expression was sheer derision. "There's no such thing as a soul."

"Then how else would you explain the fact that we're in each other's bodies?" John took a step back and put his hands on his head, desperately trying to keep himself from flailing them. "Why am I the only one freaking out about this? How can you be so calm?"

Sherlock watched him with fascination. "God, I had no idea I looked that ridiculous when I'm being unreasonable."

"I'm being unreasonable? Me?"

There was a distinct flash of irritation on Sherlock's face. "God, will you—just sit. Let's give it a go."

"Fine." John flopped into Sherlock's chair. "You opened the matchbox and then we both stared at it, and I touched your shoulder. That's when it happened, right?"

Sherlock moved to stand behind him. "Yes."

"Let's try it." John held up the matchbox and slid the cover off, but nothing happened. There was no mysterious glow – it seemed to be an ordinary matchbox again. John tilted it, looked inside, and frowned. It was quite ordinary indeed. The strike strip on the side of the box had never been used and the print on the label was of good quality. The label design seemed intentionally old-fashioned, with a stylized W prominently featured in the logo. He was reminded of the sort of matches his grandfather used to buy to light his pipe, and — he shook his head. Focus. Sherlock swore softly behind him, and John shook his head, forced himself to stop thinking. "Come on, stare at it anyway. Repeat everything just as we did it before."

It didn't work, and so they reversed positions, tried it again. Still nothing.

"Let's keep trying," John said, turning to look around the room. "You were – I mean, I was at the table to start with, and maybe it makes a difference. Maybe we should say the same words we said, exactly, reproduce the conversation."

"Exactly?" A look of panic began to spread over Sherlock's face. "I can't remember what I said."

"It was five minutes ago. How can you not remember?" John remembered every word of it, even the cadence; it was all right there in his head. If he could recall it in that sort of detail, Sherlock ought to be able to do as well.

Sherlock looked back at him blankly.

"Fuck," John said, and turned toward the fireplace. "All right, fine. So use your mind palace, see if you've got anything like this in there."

"I don't…" Sherlock shook his head, eyes wide. "It's not there."

"What do you mean, it's not there? How could it not be there?"

"It's my… whatever, me, but it's your brain. Your neural pathways, your structures." He closed his eyes and frowned, concentrating. "All of my memories are intact, but they're harder to access. I don't even know where to begin to look." He pressed his fingertips against his temples for several seconds, and then dropped his hands in defeat. "Oh, God – is this what it's like to be stupid?"

John rounded on him. "I am not stupid. And I'm having trouble in your brain as well. God, how do you get anything done when you're so easily distracted?"

"I'm not easily distracted; you just don't know how to process information quickly enough!" He whirled and leveled a kick at John's chair. "Fuck!"

"Oh, for fuck's sake, will you calm down?"

"I don't know how! I can't think straight with all this… why are you so angry?"

"I'm not angry!"

"No, I mean—" He gestured at himself, and John's jaw clenched. Of course. Sherlock was feeling the fight-or-flight response of John's body, and it was probably overwhelming.

"Oh, God, why is this happening?" John took a deep breath. "Look, just… try to control it, and then let it go. Take a deep breath. Go splash water on your face or something. Give it a moment. I don't know how else to explain it."

Sherlock made a sound of frustration, but turned toward the bathroom.

John sat on the sofa and exhaled. This was a nightmare. Perhaps a literal nightmare, and if so, he was going to be very happy in the morning. It made no sense that he was sitting here in Sherlock's body, that a fucking matchbox had done this. He didn't believe in anything remotely supernatural, had never done.

Perhaps it would wear off. Maybe after a certain amount of time, they'd switch back. Or perhaps it was like Freaky Friday and they had to learn an important lesson first. Oh, God – did they have to learn to appreciate each other's unique perspective on life or something inane like that?

The toilet flushed in the bathroom and the tap ran, and a whole fresh level of hell occurred to John. Living in each other's bodies meant they would get to know them very intimately. John groaned: there were things he didn't even want Mary to know, let alone his best friend.

Sherlock reappeared, looking a bit sheepish. He'd removed John's cardigan and had unfastened the top few buttons on his shirt, and he'd done something weird with John's hair so that it stuck up in odd places. He looked like a lunatic version of John. He settled in John's chair with a strange expression on his face.

John sighed. "What?"

Sherlock opened his mouth, hesitated a moment, and then looked up at him. "Your penis is larger than I expected."

John blinked at him for a moment, shocked, and then tried valiantly to keep a straight face. "My… what?"

"At least 20% larger." Sherlock frowned, and John couldn't help himself: he laughed. It was probably a side-effect of the tension, or the strangely tenuous hold he had on his emotions in this body, but it bubbled out, bringing tears to his eyes, and he nearly slid off the sofa.

He wiped at his eyes, still breathless from laughter. "So you're saying you've actually spent time thinking about the size of my penis?"

"I… No!"

"Expectation implies you have done."

"No, I meant… anticipated." At John's snort of laughter, he rolled his eyes and tried again. "Oh, God – would have anticipated, given your height and build." His cheeks flushed pink, and he pressed his hands against them. "Why is this embarrassing me? I don't get embarrassed about this sort of thing."

"But I do," John said, still grinning. "Under normal circumstances, I'd find this conversation excruciatingly embarrassing." The fact that he didn't seem to mind it now was rather freeing.

"Fair warning, then. You're going to be a bit disappointed when it's your turn to take a piss."

John nearly burst out laughing all over again. "How disappointed will I be?"

Sherlock scowled. "Well, not that disappointed. My penis is proportional to my body, at least."

"And mine isn't?"

"Not in my experience."

"And you've got a lot of experience with cocks, have you?" John bit his lip to stop himself from grinning.

"Yes," Sherlock replied, and John could spot the precise moment he finally caught on. "Oh, God, no, not like that. I meant with corpses."

John raised his eyebrows. "Kinky."

"Ugh, fuck off." Sherlock made a very Sherlock-like expression of disgust, and it looked utterly incongruous on John's face. He shook his head and sank back into John's chair, expression turning serious once again. "I don't know what to do, John. I don't know how to fix this."

John sighed as the reality of the situation crashed down on him once again. "Neither do I. If we're going to be stuck like this for a while, comparing penises may be the least of our difficulties."

Sherlock closed his eyes. "I don't think I could bear to be you for the rest of my life. I can't possibly solve cases like this. It would take decades to retrain your brain."

"I'm not exactly thrilled about being in your brain either. I suppose we'll have to pretend to be each other for the time being. We'd get locked up if anyone— Oh, God – Mary." He fell back against the cushions of the sofa. "How the hell am I going to explain this to her?"

As much as Mary adored Sherlock, she wouldn't want her fiancé to suddenly possess his body. He'd been lucky she'd encouraged him to continue his mad friendship of crime-solving and adventures with Sherlock, but this? This would end it. And that was if she believed them. If she didn't, if she thought the two of them had gone mad, or worse… Tears welled in his eyes and he blinked them away in annoyance.

Why the hell was he crying? He looked over at Sherlock, who quickly looked away.

"We'll figure something out," Sherlock said, a note of resolve in his voice. "She's… She seems to understand a lot of things. She loves you, and she'll…" He frowned and looked down at his hands.

"Why the hell are you trying to comfort me?"

Sherlock's expression was strained. "I have no idea."

John's stomach rumbled, and the physical sensation grounded him for a moment. The situation was ludicrous, but here he was in this body, and he needed to work with it long enough to get back to his own. Sherlock hardly took good care of himself, so John had a bit of an uphill battle to wage. He sat up again. "When was the last time you ate something?"

Sherlock thought for a long moment.

"That long ago? Well, time to rectify that." John stood and crossed to the kitchen, and opened the refrigerator. It was empty except for a few containers with questionable objects inside. He turned back to look at Sherlock, who was still sitting in John's chair and frowning. There was nothing else for it. "I think we're going to have to go out."

Sherlock turned to look at him. "That's a horrible idea."

"And yet, it has to be done. There's no reason for both of us to go. I'll pop down to the market around the corner and pick up a few things. We've got a long weekend ahead of us if we're going to figure this out."

Sherlock stood. "I don't think we should split up. We should stay together for the time being, just in case that's important."

John considered protesting, but one look at Sherlock made him bite his tongue. Sherlock radiated anxiety, nearly vibrated with it. If John felt out of sorts, he could only imagine how Sherlock must feel about being thrust into a body with a more typically functioning brain. He nodded. "All right."

Putting on each other's shoes was a strange experience, but even more bizarre was the moment John slid into Sherlock's coat. It even smelled like Sherlock, and he had to close his eyes, nearly overwhelmed. How were they going to do this? What if it was permanent? He'd been happier these last few months than he'd been in ages. His life was finally coming together, and now this had happened to fuck it all up – it was so incredibly unfair.

"Here." He turned to see Sherlock holding out his scarf. John took it and draped it around his neck, and Sherlock gave an exasperated sigh.

"You notice shockingly little, John." He stepped closer and pulled the scarf from John's neck, then folded it in half and went up on tiptoe to loop it around John's neck.

John stared back at him, reeling at the strangeness of seeing his own face from this angle, of seeing himself the way Sherlock saw him. So many details stood out to him, things he didn't see when looking in the mirror: the tiny lines around his eyes that never quite went away, but intensified in a surprisingly pleasant way when he smiled; the strands of grey in his hair that actually made him look more dignified than he would have thought; the spot on his chin he'd missed while shaving this morning, in his excitement to get dressed and get to the flat.

"There," Sherlock said, though he didn't step back. He stared up at John with an odd expression, one that made John think he was thinking about very much the same thing.

John opened the door. "Shall we?"

They were both silent during the short walk to Tesco's, and neither of them said much as they wandered the handful of aisles. Sherlock seemed content to let John fill the basket, and so he did, planning several meals in his head.

"Excuse me," he heard, and turned to see a young woman pushing a trolley. "Mind if I squeeze through?"

"Oh, sorry." John stepped back. Sherlock, however, remained in the center of the narrow aisle, just staring at her. "Sorry," John repeated, and tugged Sherlock toward him with a hand on his shoulder.

"Yes, sorry," Sherlock said, and the woman smiled at them both before walking away.

John started to turn back to the selection of veg, but stopped short when Sherlock didn't follow. John looked back at the woman's retreating figure, and then to Sherlock, whose gaze was definitely tracking the movement of her arse as she walked. She rounded the corner and Sherlock blinked and turned back to him.

"What was that?" John asked.

"What was what?"

"You were checking her out."

Sherlock frowned. "I was not."

John snorted and shook his head – and then looked away as a new thought occurred to him. Sherlock had been the one looking, and he… hadn't. She was attractive, curvy, dark-haired, confident – all the things he so often liked in a woman – and none of it had registered. He looked back to see Sherlock watching him closely through his own dark blue eyes.

"If you say so." God, it was going to be a long day. Or life. "Want to buy some wine?"

"Yes, I suppose."

Fortunately, they already knew they had similar tastes in wine, so choosing a bottle wasn't difficult. Slightly more difficult, however, was paying. Sherlock's wallet was organized using a method John could only guess at, and he finally had to hand it over to him to let him find the right card and type in the PIN. The cashier gave them an odd look, but fortunately (for her) said nothing.

Just as they reached the door, it was opened from the outside, and John nearly collided with a man who was coming in.

"Oh, sorry," the man said. He stepped back and held the door open for them, and looked up at John from under a mop of dark blonde hair.

He looked to be in his mid-thirties and was dressed as if he'd just come from the gym. He wore a long-sleeved shirt that stretched tightly over his broad shoulders, and the muscles in the arm holding the door open had clearly been sculpted through hours with a personal trainer. John's gaze trailed down his lean body before he'd quite realized what he was doing, and when he looked up again, the man was giving him a positively wicked smile.

"S-Sorry," John said, suddenly flustered, and he stepped through the door. Sherlock followed, and they both turned back to watch the man walk through it. He glanced back over his shoulder once and grinned at them before disappearing from sight.

Sherlock cleared his throat and John turned to look at him, but Sherlock only raised his eyebrows before starting down the pavement. John winced. He was usually far more discreet than that, but in Sherlock's body, he didn't have control over it.

"That was enlightening," Sherlock said after they'd rounded the corner.

"Yes it was." John took a deep breath. "So you—"

"Yeah," Sherlock replied. "And you—"

"Yes." That was far more than he'd expected to reveal in such a short period of time. And the idea that Sherlock found anyone attractive at all was… John glanced at him and Sherlock looked away, as if wanting to look anywhere but directly at John.

John couldn't really blame him. He exhaled through pursed lips and stared resolutely ahead. They would go back to the flat, and eat a meal, and then put their heads together and figure this damn thing out. And if they couldn't… well, John wasn't going to let himself think about that just yet.