Sherlock knew someone had broken into the flat as soon as he saw the front door in the street. It wasn't only that someone had crossed that door; John was still sleeping when he went out that morning, and Mrs. Hudson could have gone out too, of course. But no: although the lock wasn't broken, there was an uncommon slight bent in it, barely perceptible, and there was a tiny sliver protruding under it. These old locks are so telling and honest… I hope Mrs. Hudson never changes it for a modern one, Sherlock thought while he climbed upstairs smoothly, trying to listen to any possible odd noises coming from his flat. It's harder to tell when all you need to open a modern lock is a credit card. I would have to spend time designing some traps, and it would be rather impractical and time consuming…

His thoughts derailed when he pushed the sitting room door open and he found a completely domestic scene: John (just showered and shaved, new shaving foam, still that horrible cologne, will it ever run out? I definitely have to use it for my experiments, no matter how expensive it was or who gave it to him as a present, a woman, right? Can't remember who exactly, just one of them, women. Dark blue jumper, I like this one but he doesn't, so the good ones are at the laundry; brown jeans, brown shoes, clean, no rests of the mud from yesterday), his John, was having breakfast sitting on the sofa, his tea and pastries on the coffee table in front of him.

"Morning, Sherlock!" John greeted cheerfully. "What an early bird, considering the time we came home last night… Did you still have to wrap something up for the case?"

Sherlock stood in the middle of the sitting room, frowning, and inspected visually his surroundings. Everything seemed in order. That was… confusing.

"Yes, I wanted to take a look at the river bedding at dawn, just to check our data again …"

"Hey, what's wrong?"

Sherlock looked at him, still frowning. He hated being puzzled. Someone had entered his flat, had done something, and apparently they were gone. John would have heard them, right? Unless…

He ran upstairs, his flatmate voice pursuing him.

"Hey, Sherlock! Would you answer me? Well, take your time, who cares anyway…"

Nothing out of its place upstairs either. John's room was exactly as it ought to be. He ran downstairs again and checked his own bedroom. If they entered while John was showering, he wouldn't have heard anything at all. But then they were quick. What exactly was their objective? Bugs, hidden cameras? Poison?

"You know, I'm trying to leave some pastries for you, Sherlock", John's voice kept muttering from the sitting room; Sherlock almost deleted that noise, relegating it to a little corner of his focus. "But if you don't come here to have breakfast soon, I'll finish them. Honestly, the one day that you go out of your way and buy some pastries, I thought you would like to eat them together… Your tea is ready, so when you wish to stop acting like a lunatic and…"

"What have you said?!"

Sherlock came in the sitting room like a stampede. John shut up and raised an eyebrow in a silent question. Sherlock kneeled down almost reverently, took his magnifying glass from his coat's pocket and examined the remaining pastries. They looked perfectly normal, edible and even delicious, the pie crust variety with cream and fruits on top. Though not the kind I would have bought, John, you should have noticed. But he didn't say it aloud. He took a little piece and smelled it. Nothing out of the ordinary. With a sigh, he took a sampling bag from his coat and put one pastry inside, closing it with great care.

"So… how many of these have you eaten?" he asked John.

His friend seemed concerned now, evidently still not understanding but starting to connect the dots.

"Four", he answered with a small voice.

"Four?" Sherlock frowned still deeply. "For God's sake, John!"

"Hey, don't blame me! Who made me skip dinner last night?"

Touché, Sherlock thought, dismaying. Whatever was in the pastries, John would feel the hundred per cent of the effect. He ran towards the main door again, already deciding what kind of tests needed to be run on the pastry.

"Wait, Sherlock!"

The detective made an effort and stopped in his tracks. He was too worried to look at John's face; breath, relax; that's OK, now you can face him.

"Yes?"

John was visibly troubled and nervous, and Sherlock didn't like to see his friend like that. He tried to relax his facial expressions a bit more.

"What have I eaten? Where do those pastries come from? I really thought you had bought them."

Sherlock nodded.

"I know. Look, I don't know to whom do we owe this… present, but I'm going to take it to the lab. Stay at home, please, and I will phone you as soon as I have the results so you can take an antidote…"

John interrupted him pushing him aside and taking his own coat from the peg next to the door.

"Like hell I'm going to stay here, I'm going to the lab with you. I need to know what I have eaten. Ah, wait, I'll try to vomit it first."

"OK, try it, but I think whatever it was in the pastries is already inside your organism".

"Always the life of the party", John muttered, heading for the bathroom with his coat already on.

Ten uncomfortable minutes later, they were in a cab in their way to Barts. John looked terrible, his face showing a strange greenish tone increased by the filtered daylight inside the cab. Sherlock opened his mouth to say so, but he thought twice and decided to let it go. John would be proud of my self-restraint, I'm much less rude now than a year before, when we first met. But if I told him now, wouldn't he feel offended, since I should tell him what does he look like?

The tests needed hours, of course. Sherlock looked his usual aloof and calm self, although his mind was running a damned marathon. But for the sake of John, he tried his best to look as if nothing out of the ordinary was happening. His friend, though…

John had remained more or less calm during the first hour. But when that time passed, his determination started to crumble. He started to fidget in his chair, abandoning the magazine he was trying to read to kill time. He was sweating and his face was a poem of pain. Always so easy to read, such an open face, Sherlock thought with awe.

"You are sweating", he pointed out aloud, coming closer to John.

"Good deduction, yes", John grunted. "But a bit under your level, I'm disappointed in you, Sherlock. Yes! I'm sweating like a pig! I'm sweating so much, that even the people at the other end of the corridor must have noticed!"

He was obviously starting to panic. Sherlock fetched the tensiometer and the thermometer, and checked his vitals aloud.

"Increased body temperature. I think you are running a low fever at the moment, the thermometer will confirm it. Your glandules seem alright, your pulse is elevated… your blood pressure is really high…"

"I could have told you as much".

John was being grumpy, but it was normal under the circumstances. His arms were so sweaty that Sherlock's fingers slipped around his wrist… Hold on! His wrist seemed… more narrow. Was it the sweat? Sherlock ran his hands up his friend's arm, and John tried to stop him.

"Sherlock! What are you doing? That's a bit embarrassing, you know…"

His voice broke. Sherlock examined his friend's face, panicked, only to see his own alarm reflected in John's features. What the hell was going on?

"Sherlock?" John asked weakly. "I'm scared".

Me too, John, Sherlock thought, but refused to say it aloud. Instead he said:

"The results will be ready in a moment. Whatever it is, I will solve it. I always solve everything, don't I?"

John nodded, his open, frank face showing a faint hope. Something inside Sherlock's chest hurt at seeing it.

"Trust in me, then". The detective stood up and turned towards the lab door. "I'm going to check how the tests are doing; I'll be back in a sec."

John stood up at once, and when Sherlock glanced at him, his face was again a bit greenish.

"I'm think I'll… I need to throw up again".

And he ran to the toilet. Sherlock sighed and went back to the lab.

He poked his head out the door half an hour later. No John in sight. Sherlock frowned, took his lab coat off and went back to the corridor to look for his friend. He should take something for the fever, he must be feeling worse. But we can't afford mixing any chemicals in his organism until we know exactly which elements form the compound; there's only a twenty per cent chance of it being dangerous, but I won't take the risk.

Sherlock walked along the almost empty corridor, checking every door, until he heard a faint sob. It was coming from the toilets; it was pitched, like a child's, so it couldn't be his John, but he stepped in the men's toilet all the same. A child has entered the toilet and has found John lying on the ground; John with blood on his nose and forehead; John has passed out while vomiting; John…

Sherlock interrupted the run of possible scenarios. Because of course, he hadn't thought of that one, the one he was facing right then.

A boy around six was sitting on the floor, hugging his bony knees, sobbing. His small shoulders shook with every sob, and his entire frame looked tiny and fragile. This is because he is wearing a too large jumper, and no trousers. Because John's trousers were lying aside, along with John's shoes, and of course would be too large and unpractical to the now tiny body of John, who was wearing only his shirt and his dark blue jumper. His hair was now completely blond, without those grey streaks of his usual self, and the colour was way lighter than the tone Sherlock was used to. But his features were still his. John's. His face, so open, showing despair and absolute terror. More open, since his eyes looked huge in his small face. That's because the head grows with the rest of the body, but the eyes are the same size from birth, Sherlock rationalized, too shocked to move, to say anything. He opened his mouth to speak, but nothing came out. The only thing he seemed to be able of doing was staring at John, shrunken and rejuvenated to the point of childhood.

John reacted first. He rubbed his running nose with his sleeve and stood up. His eyes, such big, innocent eyes, stared back at Sherlock, accusing.

"What the fuck, Sherlock", he said, and his pitched, childish voice seemed so wrong with his words that Sherlock felt a bubble of laughter almost spilling off his mouth. And, the most relieving, he guessed that John had reacted exactly the same way at hearing his own voice. None of them dared to laugh, though, and Sherlock couldn't find his voice yet, so he contented himself with picking John's discarded garments up the floor and gestured John outside the toilet. John followed him, reluctantly, with streaks of tears still visible on his small round face. They walked back to the lab and closed the door behind them, aware of how the lab assistants turned to look at John and gasped in shock.

"I think we need a bigger lab", Sherlock stated, at last. He took his phone out while the lab assistants surrounded John with amazed looks. "I'm phoning my brother; I hope he has contacts to a good research lab."

The phone conversation was short, and meanwhile John was weighed, measured, taken blood and urine samples and pinched on the cheek. When Sherlock turned, John was sitting on a stretcher and wearing a lab coat his size, and was being hair ruffled by a young woman, who talked to him as if he was truly a six year old.

"…Now we are going to put this adhesive on the shot, can you press down a little? That's it! Oh, you are so cute!"

"You know I'm a 40 years old doctor, do you?"

"Sure, sure".

Sherlock chuckled. John turned to look at him, frowning, and yes, Sherlock had to agree, John looked really cute, even when angered.

"So what? Have you accomplished something phoning your brother?"

"Oh, yes! Mycroft turns out to have contacts inside the London University research labs; the government runs some research programs there, it seems, and we will have total discretion and first priority. They will be expecting us as soon as we can get there."

John's eyes opened still wider and the shadow of a smile lightened his features. But suddenly his face looked strained again. Sherlock found it quite entertaining to look at.

"Am I going to walk the streets… like this?"

And he raised his short arms, shaking the lab coat. It was indeed a tad large on him, and he wasn't wearing anything underneath, his skinny bare legs and feet sticking out of the white garment. Sherlock sighed, annoyed. The motherly lab assistant came back with a smile.

"I can lend you a pair of socks", she offered. "At least you won't be barefoot."

John gritted his teeth but forced a tight smile and a thank you. And, dressed like that –white huge lab coat and green long wool socks- he walked out the building with a brave face… that fell down completely as soon as they were in a cab.

"Why, Sherlock, why?!"

He seemed about to cry, and Sherlock felt appalled, but he didn't know what to say or how to comfort him; comforting had never been his strong point. Perhaps I should embrace him? Hold his hand? I don't know, I think the "normal" John would be embarrassed if I do. And he is feeling already embarrassed and annoyed now. So no, then.

They went inside the building in what Sherlock knew were the most awkward minutes of John's life, with lots of students gaping at them. But as soon as they went downstairs, to the labs area, the corridors and halls were quieter and almost empty. And, as Sherlock had anticipated, the lab researchers were already expecting them: as soon as they stepped in the huge, ultramodern lab, six people grabbed John and explained kindly to him the tests they were going to run on him. Sherlock was greeted by the Head Researcher.

"Mr. Holmes! Pleased to meet you! We are very honoured to be able to help you with this. I mean, we were really busy, but as your brother pointed out that our deadlines would be pushed one month forward, we are delighted to help you with such an exciting issue."

Forty-five, divorced, no children, a dog, a setter? Has been the Head Researcher for a while. He wants to publish an essay on the outcome of this… experiment.

"… Exciting, but delicate."

"Yes, yes, Mr. Holmes already told me. But he also said we could publish the results if we kept the test subject name anonymous… Would it be alright?"

The man's voice was full of concern. The detective acquiesced with a gesture and handed him the rests of the pastry in its sealed plastic bag. The Head Researcher grabbed it greedily and excused himself.

Well, now I can only wait…

He only waited two hours more. One of the youngest lab assistants kept bringing him tea, coffee and plastic enveloped sandwiches, and Sherlock considered telling him his kindness was completely useless, since he wasn't working with his brother and couldn't help him at all with his career… but the young man seemed the caring type, so perhaps he wasn't doing it only for selfish motives, after all. He drank one cup of coffee and the lab assistant grinned at him. Sherlock hoped John was getting the same caring attentions. He had been taken to a separate room with no windows and all Sherlock could do in the lab was checking the advance in the pastry analysis. The people at Barts sent him their our results to his phone, and he passed the information to the Head Researcher. That was all. He felt useless and his mood was resenting it.

Finally, two women in lab coats took John from that room and talked with the Head Researcher for a while. Sherlock approached them without waiting to be summoned. When he arrived, though, the two women left and the man smiled widely at him.

"Ah, Mr. Holmes! Well, we have all the data now. We will need time to process it and isolate the elements of the drug Dr. Watson has ingested. We are using the previous information provided by our colleagues at Barts, of course; but still, providing an antidote requires time."

"How much time?"

Both men looked down at John; Sherlock's brain would need its time to identify that tiny voice as John's one.

"A couple of days? Be certain that we will work as fast as we can."

John mouthed "A couple of days", but any sound came from his lips. His expression was of absolute misery.

"So we can go home now?" Sherlock asked. The man nodded. The detective looked the name on his plate: Dr. Carson. "Dr. Carson, I have another request for you." The researcher arched his brow, but voiced an "of course". "I need a list of all the labs in the UK capable of making this drug."

"As if I would know… Research is a competition, Mr. Holmes, so these things are very secretive…"

"This is your field, I'm sure your team and you have heard gossips about what other people are working on…"

"Alright, I'll try."

"I want the list tonight".

And with these words, Sherlock turned towards the door and started walking. Behind his back, he heard little John apologising and thanking the man, before starting to run after him.

They felt better once they were back at Baker Street. Sherlock took his coat off with a sigh and flopped on the sofa.

"At last!" he exclaimed aloud.

Then he looked at his friend. John was still standing in the middle of the sitting room with a blank face. His too large coat had dropped to the floor, and he was still wearing the lab coat and those ridiculous wool socks, covering his feet and legs almost to his knees. He looked back at Sherlock, and his eyes were vacant. Sherlock fidgeted on the sofa.

"Were you able to eat at the lab?" he asked at last.

It was already six p.m., and John had thrown up his breakfast. He had been rehydrated intravenously, and his temperature was back to normal, so if he hadn't eaten anything he should be ravenously hungry. John shook his head. Sherlock felt awkward: if they were in a normal case, John would be already in the kitchen preparing dinner and Sherlock would be left to his thoughts, so he could start planning the next steps of the investigation. But John was clearly in no state for that. Slightly annoyed, Sherlock stood up and said:

"I'll make dinner, then. What would you like to eat?"

With surprise clearly written on his face, John followed Sherlock to the kitchen. He barely reached the counter, as Sherlock registered with dismay. Would that mean that Sherlock was in charge of providing meals as long as this situation lasted? Dr. Carson, do your best and please be fast. He opened the fridge, feeling miserable. John's tiny face joined him at examining the possibilities (at his waist level, more or less): there were eggs, butter and some smoked ham. The rest of the contents couldn't be categorised as "edible".

"Sherlock, can you make me an omelette?"

Sherlock frowned. It had been a while since the last time he made an omelette, John was always the one who cooked, so… But I could made an effort and sure, why not? John's whole small frame trembled as he sighed.

"OK, just two fried eggs, then. And put that ham in a pan with a bit of butter, right? It's really easy. And fast."

And he left the kitchen, clearly annoyed. I'm the one who should be annoyed right now, he is looking down on me, how the hell does he dare? Sherlock took two pans from the cupboard, decided to show John that he could cook something as easy as fried eggs and ham, thank you very much, and that in fact, before John arrived to his life, he was perfectly able to take care of himself.

He called John to dinner ten minutes later. He set the dinnerware on the kitchen table, and watched John's reaction when his friend climbed the chair and examined his work. The fried eggs somehow have ended being scrambled eggs. Stupid, annoying eggs. But John didn't seem to care, and attacked his plate at once, clearly hungry. Sherlock relaxed a bit and sat down to eat his own share. John finished very quickly and leaned back, burping and rubbing his small rounded tummy with satisfaction.

"Thank you, it was good. God, I don't remember the last time I was so hungry! It would have been even better with tea, though…"

"Oh. You are right. But there is no milk left."

John sighed.

"I know, I had to go to the supermarket today."

"We can go now, as soon as I finish my meal", Sherlock offered, feeling generous. The look John threw at him, though, made him rethink his mood. "What? Not good?"

"Sherlock, look at me! I'm inside the body of a six year old child, and all the clothes that I own right now only fit a grown up man! So no, Sherlock, definitely not good."

Sherlock didn't know what to say. I have… to plan, the list of labs will arrive soon, and I have to investigate those labs… I want to analyse the paper in which the pastries came… This is annoying, I can't get sidetracked! But he made an effort, closed his eyes for a second and swallowed his increasing rage.

"I'll go, then. Could you make me a list of what we need?"

John nodded, relieved.

"Of course. Look, Sherlock, I'm sorry, I know this is maddening…"

Sherlock tried to smile weakly, but he ended sighing. So they finished having dinner and he went to the nearest Tesco Express while John did the dishes, standing on a chair.

"Are you sure that's not too dangerous?" Sherlock asked from the door.

John blushed, clearly grasping to the last of his adult pride, and just whispered:

"Shut up and go!"

It took Sherlock ages to find all the goods they needed. He wasn't familiar with the shop outline, and there were a lot of different brands, sizes and prices of each item. He hated it, and at the same time marvelled at how John could do the shopping so easily, as if it was nothing. He wasn't a housewife after all, he was a doctor and a soldier, a professional. If John could do it, then Sherlock could do it as well, right? No, it's not right, I hate it, there are too many inputs, too much information, too many people, I hate it and I don't want to step in a supermarket in my life again!

Then he had to carry the heavy bags home; the plastic handles dug in his hands, and something peaky from inside kept scraping his leg. As soon as John peered at him from the sofa, where he was watching a film, he commented:

"Perhaps you should have taken the shopping cart."

"Do we have one?" Sherlock grunted.

John looked at him arching his eyebrows.

"Sherlock, it's in the kitchen, exactly behind you! I can't believe you haven't even noticed it!"

The detective stared at the object, starting to feel very tired and very angry. John leapt from the sofa and came to the kitchen.

"I'll help you put the food away."

So in the end John stored all the things that went in the lower cupboards and the fridge, and Sherlock did the rest. When they were at it, Sherlock's phone went off: it was the lab list. Right, NOW at last I can start working.

"Sherlock, remember first thing in the morning is buying me some clothes…"

The detective groaned.

"You can buy them online! I have work to do!"

"They won't arrive before tomorrow morning, Sherlock, please! I won't stay at home until this is finished, I have to go out!"

Sherlock rubbed his face. This is so tiring. It can't be happening for real.

"Alright. Go and ask Mrs. Hudson where she would buy kid's clothes, please, I don't want to lose my time searching in the streets."

John's eyes widened.

"Do you think I should tell Mrs. Hudson what's going on?"

Sherlock shrugged.

"Why not. She will find out if she meets you on the stairs, after all."

The small features of John's face furrowed, and Sherlock watched him, marvelled. The range of John's reactions was still wider when he was a child, it was truly amazing! I could watch him for hours. John turned suspicious when he saw the way Sherlock was staring at him.

"What now?" he asked.

"Nothing! Go and see Mrs. Hudson, I'll start working."

It took him hours to research all the labs. The list wasn't long, but he needed to cut it down to no more than two labs. He barely noticed when John came back from Mrs. Hudson's flat and said good night, answering only with a grunt. He managed to discard most of the labs in the end, but three of them still looked suspicious. Sherlock felt triumphant anyway, and he went to have a couple of hours of sleep in high moods.

When he got up, John was already awake and sitting on the sofa with his laptop. Sherlock smirked at how big the laptop seemed, covering John's thighs completely, and how tiny his chubby hands looked trying to hold it. John raised his eyes from the screen, frowning, clearly in a bad mood, and Sherlock coughed to hide his grin.

"Good morning!" he greeted John. "Have you slept well? I'm not sure if your sleep patterns have to adjust to the new size of your body or if the adjustment is automatic."

"I have slept pretty well, thanks", John answered, angry. "But I have no clothes to wear, I can't reach the stove properly to prepare my morning coffee, and I can't reach the damned shower tap, so I haven't been able to shower, either."

"So that explains the bad mood", Sherlock sighed. "Alright, I'll start the shower water and prepare breakfast, I can do as much."

He used the loo, washed his face and then started the shower for John. His friend opened the bathroom door and peered inside shyly as soon as he heard the water.

"Come in, the water is already running."

John stepped in the bathroom and then stood there, looking uncertain.

"Do you think you need something else?"

John frowned again, wondering about it.

"I don't think so, no". His lab coat was already sliding down his tiny shoulders when he froze. "Sherlock? Would you mind?"

And he pointed out of the room with his head. Sherlock chuckled again and stepped out, only to stop and turn again at the door.

"I was so interested in knowing how your body was when you were six, John…"

"Out!"

And a soap bar passed flying over Sherlock's head.

Alright. Coffee: done. Toasts: in the toaster. Take out butter and jam. And sugar. And…

"Sherlock!"

A childish shout took Sherlock off his thoughts.

"Coming!"

John was out of the bath, standing on top of the mat, trying to cover himself with the shower curtain. The transparent plastic shower curtain.

"I… I can't reach my bathrobe", he explained in a tiny voice.

Sherlock handed it to him.

"You know, you should stop being so embarrassed right now", he advised John. "I am aware of how private and modest you usually are, but we are in a complicated situation at the moment. Did your six year old self have any physical defect that would embarrass you?"

"That would embarrass me more than the fact of having a six years old body? Nah, I don't think so".

And John let go of the curtain with a sigh and took the now huge bathrobe. Sherlock watched him, grinning. John was chubby, all rounded shapes, still with baby fat at the right places, and although Sherlock wasn't one for fawning over small children, he regretted right then not having accompanied John to visit Mrs. Hudson the night before. He was sure that, after the initial shock, the old lady had pinched those rosy cheeks. And he hadn't been able to see it!

"Sherlock, what is that smell?"

Smell?

"Shit, the toasts!"

They had coffee and burnt toasts for breakfast. With a double serving of jam, it wasn't so bad, was it? Sherlock sent John a hopeful smile, being reciprocated by a long-suffering look from John.