AN: Urban fantasy AU. Title from The Tallest Man on Earth's "Wild Hunt". Written for the 'hide and seek' challenge at fan_flashworks.
Sherlock swallowed the potion and shuddered expressively. "Urgh! Why am I the one taking this?"
"Because I am, and I quote, 'far too unobservant to waste this potion on'," John replied sardonically, taking a somewhat malicious pleasure in the faces his friend was pulling.
"As I recall, you refused first and claimed you would never in a million years drink some experiment of mine," Sherlock retorted, then yelped as his body began to shrink. John started forward in alarm, but was waved back, and confined himself to watching nervously as the years seemed to fly off Sherlock until a ten-year-old was standing in his place.
"I still don't see why all this is necessary," John said.
Sherlock rolled his eyes, the familiarity of the expression disconcerting on the childish face. "How else am I supposed to discover how children are being abducted from the park? You were the one who vetoed ordinary surveillance, remember?"
As he spoke, he'd begun to divest himself of his now overlarge clothing. John turned around to give him privacy, replying, "Ah, yes. Because two grown men covertly watching schoolchildren was a fantastic idea, not at all suspicious."
"As ever, you fixate on the already resolved and ignore the matter at hand." The snide remarks, John decided, were - impossible as it seemed - even more annoying in the high, unbroken voice.
"You need to take me to the park before this wears off," Sherlock continued as, now dressed in more suitable clothes, he strode around John and made for the door. "The disappearances seem to be connected to games of hide and seek, so I'll attempt to initiate one and observe what happens; I suspect - what, John?" he snapped, seeing him shake his head wordlessly.
"Have you any idea how strange it is to see a child talk like - well, you?"
"I am me. What's your point?"
"You're going to get some odd looks at the very least if you talk like that to children. Can't you try and sound more your age - or rather your apparent age?"
Sherlock looked at him, baffled. "This is how I talked when I was ten."
"Yes, but you're probably a changeling," John said. "Can't you try and sound more human?"
He'd mainly meant to tease, but Sherlock frowned thoughtfully. "Good point. If I'm right and some creature of the Fae is involved in this, I don't want to make it suspect I'm anything but what I seem. I'll try to sound more infantile."
"You could start by not using words like 'infantile'," John suggested. "And I'm not convinced about this 'hide-and-seek' plan, what if you get kidnapped?"
"I may currently look and act like it, but I'm not actually some idiot child who'll step into a fairy ring, or be lured away by fantastical visions. Now come on! We're going to the park." Without waiting any longer, he took off down the stairs.
"What's that quote about the children of today being tyrants?" John asked of the empty air. Before following his friend, he checked his revolver was in his pocket. 'Minding' Sherlock would give him a good excuse to be watching what went on at the park; and Sherlock might be as (over)confident in his mental abilities as ever, but John put plenty of faith into Cold Steel.