Sherlock wasn't entirely sure how it had happened. One minute John was normal, and the next he...wasn't?

There was a flash of light as one of the machines in the lab activated. Sherlock heard a zapping noise, and suddenly John was gone.

Nope, scratch that. He was still there. He was just...a child!

Yep. The army doctor glory of John Watson had just morphed into a blue-eyed, sandy-haired five-year-old. Sherlock glanced down at the child, who was the spitting image of a tiny John, complete with a child-sized bomber jacket. Well, obviously. Sherlock thought. He is a tiny John.

Little John looked up at Sherlock with an equally confused expression, "Why are you looking at me like that?" John seemed to finally realize the startling height difference. "Wait a moment, did you get taller?"

"No," Sherlock replied. "You've gotten quite a bit shorter. And younger, in fact."

"What?" Sherlock pulled out his phone and snapped a picture of the new John. He held it out for the child to see. "Oh my God! What...?"

Sherlock stepped cautiously towards the machine that had flashed, wary of the consequences of setting it off again. It looked like some kind of laser contraption. Maybe he and John had accidentally set it off. After all, they weren't exactly supposed to be here.

It was all for a case, as usual. A man (size 11 shoe, slight limp, science background) had been injecting his victims with a slow-acting poison. Sherlock had deduced that the man must work in some sort of lab, so he had started with the biggest one in London: the laboratory in the basement of Bart's. Evidently, Bart's lab was home to much more than just medical research.

Sherlock didn't see any kind of switch labeled 'Fix My Blogger' so he swiped three of the notebooks next to the device. He turned back to John, who was quickly beginning to lose his composure. "John, I can fix this. Let's go back to Baker Street, and I'll figure this out."

John only nodded. As they left through the back entrance- people would definitely talk if they saw this- Sherlock saw John pinch himself a couple of times, obviously hoping he was dreaming.

Back at 221B, Sherlock set to work on his experiments. He took a sample of John's hair and skin, and he cut a piece off of the jacket. He ran his tests while John just stared at the wall. All of the trails came back normal. John had been turned into a normal kid.

"Why can't we just go back to the lab and explain what happened?" John asked after Sherlock had told him what he'd found. "They can fix me."

"What if you're the first successful human trial, John?" Sherlock had already considered this. "They won't just turn you back, they'd want to study you. Besides, they may not even be able to change you back."

"Then what do we do?" John cried. "I can't stay like this forever! What did the notebooks say?"

"Turns out they were for the expresso machine prototype, not really useful to us at the moment."

A knock at the front door startled them both. They heard Mrs. Hudson answer it, and then footsteps began climbing the stairs. John bolted for the closest hiding place, Sherlock's bedroom. The door clicked shut softly behind him just as the man entered the flat.

"Are you Sherlock Holmes?" The man carried what looked like a medical bag. He had been dispatched in a hurry, considering the state of his jacket. He had had a bad experience with the kettle this morning, leaving spots of tea on his shirt cuffs. Slight circles under his eyes indicated he was up late the night before.

"I am. Who are you?"

"I've been sent by your brother. Something about a mishap with a de-aging ray?"

Sherlock's bedroom door opened, and John emerged. The man looked him over when he walked in. "Ah, yes. Now, Dr. Watson, if you don't mind, I'd like to give you a quick examination."

The man poked and prodded John for about ten minutes. He took more samples of his DNA. He left after assuring John that Mycroft was doing what he could to help.

"What do we do in the meantime?" John wondered aloud. "I can't go out like this!"

"Why not? Just explain that you're still you, it won't make a difference."

"Sherlock, I can't just go around telling people I've been de-aged. They'll think you've murdered me, replaced me with a five-year-old, and gone barking mad!"

"I see no reason why I can't still take you out on cases with me." Sherlock said honestly. John was still John, just a little shorter. But he still harbored his bravery, selflessness, and kindness, the qualities Sherlock admired in him.

"I'm four-and-a-half feet tall, Sherlock." John said matter-of-factly. "How do you expect me to keep up with you when you go chasing criminals across London? Hell, I can't even reach the cabinets to make a meal."

"You can still come to the crime scenes. They don't usually require running."

"You can't take a child to a crime scene!"

"You're not a child. You're still you."

"You know that, and I know that. But I'm certainly not going to be explaining this to anyone else."

"How long do you think you can hide?" Sherlock retorted. "Mycroft and his minions already know. It's just a matter of time before Lestrade or Mrs. Hudson sees you."

"I will cross that bridge if I come to it. At the moment, I'm more worried about how I'm going to survive in the flat for awhile. If I can't reach the food or make a decent cup of tea, how will I function? I'm too small to do the things I normally do."

"You'll manage," Sherlock assured him. "I'm sure we have a stool around here somewhere."

After a few minutes of silence, John spoke again, "How long will I have to be like this, Sherlock? I don't think I can stand being a child forever."

"Don't worry, all the king's horses and all the king's men are onto it." Sherlock remarked lightly.

"Yes, but remember," John said solemnly. "They couldn't put Humpty back together again."