John couldn't stop staring at himself. Was that really what he'd looked like back then? The shirt he'd gone to bed in hung loosely from his shoulders, thinner, less muscular arms escaping from the baggy sleeves. His pajama bottoms were barely managing to stay on his hips.

"Sherlock?" John finally called out once the shock wore off to something manageable, the sound of footsteps walking slowly up the stairs letting him know ahead of time where Sherlock was with the situation.

When Sherlock got to John's door, the first words out of his mouth were, "So you too then? Interesting."

Now John's focus was locked on his flat-mate. Or rather, the version of his flat-mate that looked a bit too tall for his body, lankier even than John was at present, and with a mess of black curls that put his usual fringe to shame. Add that to the lack of sharpness in his usually angular features and John could almost say that Sherlock looked… pretty. Strangely, surprisingly pretty. "What's going on, Sherlock?" John swallowed.

Sherlock just looked John up and down before muttering, "About sixteen, you'd say?"

"I don't know, maybe? How is this even-?" John tried to reply, but Sherlock was walking towards him then, reaching for the collar of his shirt and pulling it down, over, revealing the strip of smooth, bare skin at John's shoulder where a scar had once mangled the flesh. John ran his hand over it in awe, rolling his shoulder back once and marveling at the lack of tension. Hell, the lack of anything resembling stiffness in any part of his body, for that matter. Sixteen… He'd gone to bed last night nearing forty and had woken up a bloody teenager.

Sherlock took a step back and nodded, pulling the waistband of his own pajama bottoms away from his hips and looking inside. "That makes me fifteen."

John blanched. "How can you tell from… um, from your-?"

Sherlock rolled his eyes and let the waistband snap back into place. "Appendicitis, John. I had mine removed when I was sixteen. No scar, but the acid burn on my fingers from an experiment when I was fourteen is still there. So that makes me somewhere in the vicinity of fifteen."

"But how is that possible? How is any of this possible, Sherlock?" John ran a hand over his face, sitting down heavily on the edge of the bed and willing himself not to panic. Sherlock shook his head, frowning.

"It shouldn't be. And yet here we are."

Sherlock couldn't seem to stop pacing; from one end of the room to the other, in circles, in place, if that were possible. So John tried to busy himself by not watching, making tea instead maybe, but when he opened up the cupboard, everything was a few inches too high.

"Dammit," John swore, closing the cupboard with no little amount of force. Even a bloody cup of tea wasn't going to make the whole ordeal less surreal, apparently. He hadn't reached his last growth spurt until about two years from then, from now, from wherever the bloody fuck. "Dammit all."

"Not helping!" Sherlock yelled from the sitting room. "I can't think!"

"Yeah? Well I can't reach the soy sauce on the top shelf anymore, so sod off!" John yelled back.

"What on earth do you need the soy sauce for?" The irritation in Sherlock's voice was almost palpable. Then no more than a second of following silence before, "You've never been particularly self-conscious about your height before. Why mourn the loss of a few more inches?"

John groaned, resting both hands on either side of the sink and letting his head hang between his arms. "That's not the point and you know it."

"No actually. I don't." Sherlock's voice was closer now, lingering at the entrance to the kitchen.

"You can't possibly think what's happened to us is normal."

"Of course not."

John could practically hear Sherlock rolling his eyes. It made the anxiety in his chest tighten that much further, enough to have him spinning to face Sherlock defensively. "Then how the hell are you being so bloody calm?"

"Because I can see the benefit in all this, something which you've failed to recognize in your panic." Sherlock's words were steady and collected, genuinely at ease with the situation where John felt about ready to crawl out of his skin. The look in Sherlock's eyes was damn near electric. John sighed.

"Well go on then," He gestured at the air between them. "What's the magic benefit that makes this whole fiasco bearable?"

Sherlock's grin should have been answer enough. Almost was. "We've been given a second perspective on adolescence. A renewed objective on the mysteries of youth. Just think of the experiments, John!"

"Of course," John sighed. "And don't forget reliving puberty, having to hide from Mrs. Hudson, Lestrade… What are we supposed to do, Sherlock?" The argument was obvious in Sherlock's stance, on the look on his eyes, the tight draw of his mouth. So John kept on before Sherlock could make that argument known. "I have no doubt you'll figure out a way to get us back to our actual ages, but until then. What are we supposed to do until then?"

Sherlock was quiet for long enough that John though he might not have understood the question. Add that to the way he stood, half leaning against the entryway to the kitchen, half sliding down to the floor, palms clasped with fingers pressed to his lips in familiar Sherlockian gesticulation, and John thought he very well might have broken him. But then, after enough time that John began to rethink that aggravating cuppa, Sherlock finally nodded, as if to himself. John paused to watch him, wrong mug in hand because Sherlock had put his on the top shelf in an awkward attempt at apology dishwasher emptying. His favorite mug was out of reach just enough to be infuriating.

"We enroll in secondary school," Sherlock said, as if it was the most obvious decision in the world. When John gave him his usual, 'Care to explain for the peanut gallery?' look, Sherlock grinned. Actually grinned. "What better way to understand the complexities of todays oppressed and malcontented youths than by experiencing it in person?"

John liked to think he'd put up a damn good fight against Sherlock's latest hair-brained scheme, but in all honesty, he'd folded about as quickly as a gambler with a sixteen in blackjack. It wasn't that he thought Sherlock had a point. Far from it. It was the little things: reliving his rugby days, being fit and young again, working off of a clean and-thanks to Sherlock's technological tampering-untraceably unknown slate. Sure, he had no desire to live through the tail end of puberty again, but he trusted Sherlock to get them back to rights before then. God help him, but John trusted him more than anyone.

"So, right now, you have an art and compositions class, while I have chemistry 101," Sherlock explained, holding up the map of the local secondary school and their individual schedules all in one hand like a deck of cards. Ironic.

"Why the hell would you sign me up for an art class?" John asked, not really caring all that much.

"You seemed to immensely enjoy the few you took in primary school," Sherlock explained off handedly. "I figured the best way to experience this would be to rekindle old passions."

"Thus the chemistry." John didn't want to know how Sherlock had found out about his primary school art classes-more like finger painting, really-but it made sense, on some strange, otherworldly level. He could already see Sherlock berating the other kids in his class the same way he trolled the opinionated internet sites between cases; ripping the assumedly knowledgeable to shreds and rebuilding their damaged psyches with acerbic wit and crippling truths about their upbringing. John breathed out a tired laugh, turning towards the Arts wing. Before he left completely, however, he turned towards Sherlock and grabbed his wrist.

"Promise me you'll figure out a way to change us back sooner rather than later."

"Of course, of course," Sherlock waved him off in a way that clearly meant, "When I'm good an ready." John tightened his grip.

"Promise me," John tried again, setting his gaze heavy and stern, immovable. They'd gone to a lot of trouble to be sure that Lestrade and the Yard wouldn't be looking for them or asking questions, that Mrs. Hudson wouldn't assume the worst if they were strangely quiet for the next few weeks, but the precautions they'd put in place wouldn't last forever. "Your word, Sherlock."

Sherlock scanned his face with an honest seriousness John had come to relate mostly to cases and instances of social fundamentalism that Sherlock didn't understand but wanted to; not that he'd ever admit it. Eventually he nodded. "You have my word," he said, and then he disappeared down the hallway which led to the Science wing.

Art in secondary school was an exponentially different experience in comparison to what little he remembered from primary. For one, it was hard. And frustrating. It didn't necessarily help that he was coming into this particular class midway through the year, but John still would have thought himself at least passably competent before. Now, he wouldn't have been surprised to never pick up a brush again.

"Are you working on the teapot?" A girl to his left asked him almost shyly. She wore frameless glasses and had long blond hair tied back behind her head with a light blue scrunchie. She reminded him instantly of Molly.

"One of the trainers, actually," John sighed, frowning at the shoe for good measure before putting his brush down with a defeated shake of the head. The girl blushed.

"That's what I meant," she backpedaled, clearing her throat. "It looks good. You're doing good." John couldn't help but laugh.

"I'm not insane enough to think it looks anything like a shoe." He smirked and held out his hand. "But thanks. I'm John." She took his hand and shook it lightly, letting go with a timid smile.

"Lisa," she offered back, tucking a loose blond curl behind her ear. "So where'd you transfer from?"

"John Hudson?" A voice called suddenly from the doorway before John could come up with a backstory. He almost didn't respond; they'd decided on the last name as a precaution, just in case they needed someone to play the part of their mother. After a few second delay-and Lisa's questioning gaze-John stood, walking up to the teacher lingering at the entrance to the classroom, a look of discontent on his mousy-looking face.

"Yes, sir?" John asked, aiming for polite. The teacher looked him up and down once before walking out the door without a word. John glanced back at Lisa and shrugged before following suit.

Once they were a good distance away, the only ones in this portion of the hallway, the teacher huffed out an aggravated, "You're the only one on his emergency contact, and since you're here, we have no other means of removing him from campus. Outside of involving security." John had expected something like this to happen eventually, but even he was shocked by how quickly Sherlock had managed it.

Confirming his suspicions, the teacher led him straight to the headmaster's office, the sound of an argument echoing loudly from behind the closed door. John sighed, pinching at the bridge of his nose. "What did he do?" he asked as the teacher reached for the doorknob, pausing to offer John an exhausted glance.

"What didn't he do?"

John let his hand slap against the table like an outburst. Sherlock didn't seem fazed, which only made John angrier. "We've only been here two hours, Sherlock!" John added instead, breaking his irritation down for the lanky once-again-teen. "How the bloody hell did you manage to insult the entirety of the Science wing's instructors and half its students in two hours?"

"It's not my fault they're all idiots," Sherlock snorted, leaning back in his chair. The mousy-faced teacher and the headmaster had left John to "deal with" him in an empty classroom for the remainder of the period. It was either that or contact Mrs. Hudson, and they hadn't exactly updated her on their current predicament yet. Barely a few hours into the day and Sherlock was already a poorly timed deduction away from being expelled. Why they'd even bothered-or more specifically, why Sherlock had ever thought this a good idea-was beyond John's level of comprehension. Surely Sherlock had his reasons for them being here, experiments or not, but it was starting to become less enlightening and more like torture.

"You're the one who wanted to experience the joys of modern day secondary school," John groaned. "What's the point if you're just going to get us thrown out on day one?"

Sherlock rolled his eyes. "It's not just about the experience." The 'obviously' was implied, as always. "It's about the data most will never have the opportunity to objectively uncover. Forgive me for not sitting back and letting the opportunity be wasted by pitiable academic protocol."

"I get that you want to study the minds of the modern teenager," John tried. "But don't you think it would benefit you more if you used those acting skills you're always flaunting to try to fit in instead of alienating yourself?"

The expression that flashed, however briefly, across Sherlock's features managed to lodge the rest of John's argument firmly in his throat. And if that hadn't, the words Sherlock uttered next, softly and like a confession, would have done the trick.

"This was how I was during my schooling," he cleared his throat, sitting a little straighter. "I was merely drawing on personal experience to make the situation seem more believable."

John could have kicked himself.

"Look… Sherlock, I-" He tried to say clearing his throat awkwardly, but Sherlock's groan cut him off.

"Don't patronize me with your misdirected notions of sympathy," he rolled his eyes, looking almost like himself again. "I'm well aware that my behavior at that age was considered abnormal and brash. I simply chose not to care."

"And so they called you a sociopath," John nodded, still feeling a bit guilty for pouring salt in old wounds, even if Sherlock pretended they didn't exist. He knew the man-teen?-well enough by now.

"I called myself a sociopath," Sherlock corrected, running a hand through long black curls and letting the strands fall into his eyes in a way that looked totally intentional. "The opinions of my peers, my instructors, my family. I valued none higher than my own, so I saw little point in putting on some sort of idealized façade just to "fit in." That was always Mycroft's area of expertise."

"That couldn't have been easy, though," John mumbled. "You didn't even have one friend?"

"Obviously."

"But-"

"And also irrelevant. It would have distracted me from my experiments."

"You're probably right," John sighed, feeling oddly hurt by that for some reason. "We should get back to class if you want to see this experiment go anywhere."

"Quite right." Sherlock stood, straightening out the uniform they'd acquired once Sherlock had picked the school they'd been infiltrating. John had to admit, it looked better on Sherlock than it did on him. A lot better. John swallowed, walking to the classroom door first. He reached for the handle and paused.

"I would have." John said suddenly, surprising himself. He hadn't really meant to speak, just a passing thought, but it was out in the open now. Expectedly, Sherlock didn't reply, waiting for him to continue. So he did. "Been your friend, I mean." He turned around, forcing himself to look Sherlock in the eye. "If things had been different, if we'd met when we were young. I would have been your friend."

Sherlock looked… almost confused. "You would have hated me."

"Probably," John smirked. "But that doesn't mean I wouldn't have been your friend anyway."

"That doesn't make sense," Sherlock frowned. "You can't possibly know how I was back then."

"Not too different from how you are now, I imagine." John was full on smiling now. "And I was a lot more stubborn when I was… Well, this age." He gestured at himself in a sweeping motion, caught off guard by the way Sherlock's eyes followed the line of his body. "I would have… um…" John's own uniform was suddenly stifling, too tight around the neck, strangely warm. He swallowed, throat catching on a barely contained gasp as Sherlock licked his lips. His eyes were set wide, a little lost, a look John never expected to see on Sherlock's all knowing face, though the effect was lessened by the fact that that same face appeared literally fifteen years younger than it had the night before. "I'm sure we would have…"

"John-" Sherlock whispered, licking his lips again, and John couldn't stop staring at them. Why couldn't he stop staring at them?

It took him a stupidly long time to realize he was getting hard.

"We should call this off," John turned back towards the door, panicked. Maybe in his original body, his older, more experienced body, he'd have been able to fight off this sudden attraction to the pretty-faced version of his suddenly-young flat-mate. But in the body of a hormone-riddled teenager, he didn't stand a bloody chance. "We should come up with a better plan, maybe. Go somewhere else, to separate schools. More variables, more data for your experiment. I'll just-"

"John." Sherlock's voice was closer now. Too close. And sure, the man-teen-was pretty, very pretty, so pretty it hurt, but he was still Sherlock, and John had never had these sorts of feelings for him before, well maybe not intentionally, admittedly, and just because they looked like kids right now didn't change the fact that they still had the minds of adults so surely this was some strange form of pedophilia and this couldn't happen, Sherlock wouldn't want it to happen, this couldn't happen, wouldn't happen, shouldn't happen. "John."

A hand on his shoulder made everything stop. The chaos spinning in his mind settled just as his body settled beneath that touch, the warmth of Sherlock's hand bleeding through the uniform blazer and making his skin tingle. Still, John couldn't bring himself to turn around, not sure what he would do once he did. Not sure what look would be on Sherlock's face. Repulsion? Frustration? Confusion? Excitement?

Agreement?

"I would have been lucky," Sherlock said instead, removing his hand. His presence noticeably shifted as he stepped away, leaving John feeling almost cold. Slowly, John turned around, willing his heart to stop racing. Sherlock wasn't looking at him, hands buried in the pockets of his trousers and shoulders tense. John swallowed.

"Lucky?" He pried. Because for some reason he couldn't explain, he needed to know.

Sherlock did look at him then, something unfamiliar and yet instantly recognizable in those piercing grey eyes. "To have had a friend like you. Back then." The corner of his mouth curved just slightly upward. "I would have been the luckiest boy in London."

It was corny and awkward and filled with enough sentiment to probably fill the man's quota for the next ten years, but it was all John apparently needed. In one stride, he was within Sherlock's personal space, gripping tightly at his lapels, and dragging him down into a fierce, overly enthusiastic kiss.

Sherlock seemed unable to respond at first, the shock of it keeping his lips frozen just enough apart for John to dip the tip of his tongue between. Which seemed to wake Sherlock up with a shiver, his lips parting further, sucking John's tongue in greedily before kissing back with just as much fervor.

For a moment, John pulled back, admiring the dazed look on Sherlock's face, his kiss-bruised lips still wet and shining. He couldn't help himself. "I went to school in Brentwood." Sherlock frowned, opening his mouth in intended retort, but John simply busied that mouth with his tongue once more, kissing away the tease. When he pulled back again, Sherlock was practically melting against him, his hands wrapped around John's back, pulling him in, keeping him there. "I'd have been pretty lucky too," John smiled. "But I already consider myself the luckiest man in London just for having met you at all."

John paused then, waiting for the jibe to his own moment of sentiment, but Sherlock just smirked, pushing John against the classroom door and wedging his knee between John's legs in a beautiful flash of pleasure. "Don't you mean luckiest boy?" He grinned, rocking his hips as his hands began to roam. John clung desperately to Sherlock's shoulders once those hands found the bulge in his trousers, cupping lightly.

"Fuck you," John panted, all bite in the words diminished by his arching into that touch. "Just because I look sixteen doesn't mean I'm not still a man."

"Feeling a bit emasculated?" Sherlock chuckled darkly, punctuating his words with the quick undoing of John's zip and the wrapping of long, talented fingers around his achingly hard cock.

"You wish," John growled, thrusting into that grip as he all but attacked Sherlock's mouth, worrying Sherlock's bottom lips between his teeth. But it wasn't enough. He needed more of Sherlock, everything Sherlock, inside, outside, around him, closer, so much closer. So, without giving himself much time to dwell, John reached between their bodies and followed Sherlock's lead, undoing his trousers and pulling out his length to slide against John's own. The difference in sensation was breathtaking, dizzying, especially as Sherlock wrapped a hand around them both, pumping them together, bringing them both closer and closer to the edge.

"J-John," Sherlock breathed against John's mouth, lips trembling and eyes half-closed. John let his head fall to Sherlock's shoulder, dragging his teeth against the portion of Sherlock's neck not covered by the aggravating uniform collar.

"Just a bit… Just a bit…" John groaned, laying his hand over Sherlock's and joining him in the steadily quickening strokes. "Beautiful, Sherlock. Just a bit more. Beautiful."

"John, I-" Sherlock gasped, hand faltering as he came, spilling between them and adding a delicious glide to John's final few strokes, his own orgasm ripping through him with an intensity he hadn't felt in years. Whether that was his sixteen year old body or Sherlock's hand still wrapped loosely around his cock, John wasn't sure. Probably both.

"That was…" John tried, but there were no words. Unexpected? Complicated? Remarkable?

Everything he never realized he'd wanted? Yeah. Keeping that one to himself.

"Messy," Sherlock frowned, looking down at his hand, making to wipe it on John's blazer, but John backed away.

"Oi! Just hang on a second, will you?" John frowned right back, snagging a paper towel from a dispenser next to the sink. "Here," he mumbled, wiping at Sherlock's hand before taking care of his own, his smile uncertain. He hadn't expected the sentiment to last long, but he'd hoped they'd get at least a bit of cozy afterglow going. Though, John thought sadly-and more than a bit worriedly-perhaps that had been simply part of the experiment. All part of the objective collection of data. It was stupid of him to think it would be otherwise. Stupid.

"You're thinking very loudly," Sherlock said, suddenly back to standing much, much too close. Though, this time, John couldn't bring himself to want to step away.

"I'll try to keep my thoughts to a whisper, then, shall I?" John tried for sarcastic but barely managed teasing, his voice no more than a whisper itself. Sherlock was looking at him with the same intense focus he gave fresh corpses and cold cases. John wasn't sure if it was a good thing that he found that incredibly erotic.

"Never quiet your mind, John," Sherlock whispered back, leaning in until their lips were almost, almost touching. Just barely, not quite, a sliver of space between still slightly labored breaths. "It's one of your most attractive qualities."

"I'm sure, compared to yours-"

"Your mind will never be like mine," Sherlock interrupted, the insult quickly wiped away by his following words. "And mine will never be like yours. You surprise me, John Watson. Every day, your mind finds new ways to surprise me."

"Just my mind, then?" John scoffed. "That's the only thing about me you find attractive?" It was meant to be flirty, teasing, but the question was real, sincere. John had to force himself not to wince at how he sounded. Just like a love-struck teenager.

But Sherlock covered the final breath of space between them in a kiss that was almost tender, intimately so. "Among other things."

This time, the kiss was slower, deeper, not nearly as desperate or filthy. But that didn't mean they weren't panting against each other again in minutes. Another aspect of the teenage body John didn't know whether to praise or curse. Of course, they weren't given much time this round before the bell was chiming persistently over their heads, the sounds of students filing out into the hallway making themselves known. John pulled away with a groan, forcing his erection back into his pants in a way that he hoped wouldn't be noticeable before helping Sherlock do the same. As John turned to the door, however, Sherlock snagged him back by the wrist.

"Surely the experiment has been conducted enough for today."

John grinned. "And tomorrow too, I'd imagine."

"Home then?"

"Home."

They didn't return to secondary school for two weeks, and only then to locate the budding pagan who'd managed to stumble across a functioning book of spells. She swore she'd been unaware of its power-and its targets-offering to change them back as soon as she worked out how to do the spell properly.

A few hours later, they'd been transformed back to their normal ages, and the book-as well as its owner-had been handed off to Lestrade. Or so John had thought.

"The case is solved, we're back to normal, Lestrade can handle the tedious details," Sherlock sighed before disappearing into his room. He didn't come out for the rest of the day, even after John's ignored attempts at getting him to come outside for dinner. And dessert. John tried not to assume Sherlock's attraction to him had ended with their newly aquired youth, but the thought lingered.

That is, until John was awoken to the feel of a hot mouth sucking greedily around his prick.

"Oh fuck, Sherlock!" John groaned, forcing himself not to thrust even as his hands buried themselves in Sherlock's hair. "Wh-What are you-?" Of course, the half-question had the damnable consequence of Sherlock removing his mouth to answer.

"Waiting for you to wake up so I can practice."

"Practice what?" John flipped on the light and licked his lips, the sight of Sherlock between his legs almost enough to do him in then and there. "Giving me head?"

"Of course not," Sherlock rolled his eyes as if to say he was already experienced enough in that area, a though that had John's dick twitching in response.

"What then?" John cleared his throat, hoping the answer would involve Sherlock's mouth returning to his already painfully hard erection. Instead, Sherlock answered not with words but with a thought. A thought inside of John's head.

Can you hear me, John?

John blinked. Holy mother of fuck!

Ah, good. I can hear you too. Sherlock chuckled, grinning proudly. And deviously. "Both aspects of telepathy mastered in under ten hours. And they say magic isn't a science."

"Magic shouldn't even exist, Sherlock! How are you even-?" John forced himself more completely upright. "The book. You kept the fucking book?" John ran a hand over his face. "That book is dangerous, Sherlock! You can't just mess around with something like that. Last time it was teenagers, next time it could be dogs, if you're not careful!"

"I'm always careful," Sherlock rolled his eyes. "Now do me a favor and try to think in complete sentences."

"Excuse me?" Even John's eyebrow raise faltered as Sherlock swallowed him back down at once, sucking lightly but with renewed vigor.

Tell me what you want, John. Everything you want.

John couldn't hold back, didn't know how, not when every press of Sherlock's tongue against the underside of his shaft sent flashes of pleasure up his spine and pleading thoughts through his head. Oh God, Sherlock!

John didn't know it was possible to come three times in a row; maybe that was something Sherlock had read in the book too. But he hadn't thought telepathy and a de-aging spell was possible either three weeks ago, so John figured it best to pick his battles. Especially the ones that put Sherlock Holmes in his bed. He could already tell this whole magic thing was going to drive him up the wall, but he'd be lying if he said he wasn't at least grateful to it for that.