"This takes place during the case in The Reichenbach Fall episode where the two children go missing, only it will be three this time. In the Harry Potter universe, this happens during the summer after his first year at Hogwarts. I hope y'all enjoy this little story! Oh, this will have no romantic pairings in it by the way.

Sherlock's POV
Lestrade had come to me about a kidnapping when John returned from-wherever he went.
"Sherlock, something weird-"
John cut himself off.
"What's going on?"
"Kidnapping" I immediately replied.
"Rufus Bruhl, ambassador to the US." Lestrade explained to him.
"He's in Washington, isn't he?" John quickly replied.
"Not him, his children," Lestrade interrupted. "Max and Claudette, aged seven and nine. They're at St. Aldane's.
"Posh boarding place down in Surrey." Donovan added.
"School broke up. All the other boarders went home," Lestrade continued. "Just a few kids remained. Including those two."
"The kids have vanished," Donovan added, obviously I might add.
"The ambassador's asked for you personally," Lestrade said to me in a frustrated tone.
"The Reichenbach hero," Donovan said sarcastically.
I didn't respond, but simply left the flat, overhearing how happy Lestrade was to be working with a celebrity. Don't know what he was talking about.
Donovan drove us in her car to the school.
"Miss MacKenzie, House Mistress," Lestrade explained to me as we walked up to a middle-aged woman sitting by an ambulance with a shock blanket.
"Go easy," he added.
I didn't listen to him, however. Two kids were kidnapped, and I needed her to speak quickly in order to get on with the investigation.
"Miss MacKenzie, you're in charge of pupil welfare, yet you left this place wide open last night! What are you, and idiot, a drunk, or a criminal!?" I demanded, my voice getting progressively louder as I spoke.
"Now quickly! Tell me!" I yelled, ripping off the shock blanket.
She was in tears, but I could care less at the moment.
"All the doors and windows were properly bolted! No one, not even me, went into their room last night. You have to believe me!" she said tearfully.
My angry persona immediately dropped.

"I do I just wanted you to speak quickly." I said to her. "Miss MacKenzie will need to breathe into a bag now." I called to the medical team.

Then, I moved on into the school.
"Six grand a term, you'd expect them to keep the kids safe for you." John said, a tad condescendingly.
"So the other kids had all left on their holidays?" he asked Lestrade, who had just entered the girl's room that I was inspecting.
"They were the only two sleeping on this floor," Lestrade replied. "Absolutely no sign of a break-in. The intruder must have hidden inside someplace."
I started looking through her things, when I found something. It was a brown paper package, with red seal on the front. Inside it was a book, Grimm's Fairy Tales. This might be something.
I flipped through it.
"Show me where the brother slept," was all I said.
Once there, I examined the room.
"The boy sleeps there every night," I said, more to myself than the people in the room. "gazing at the only light source outside in the corridor. He'd recognize every shape, every outline. The silhouette of everyone who came to the door." I explained.
"Okay, so..." Lestrade begins.
I interrupt him.
"So, someone approaches the door who he doesn't recognize. An intruder. Maybe he can even see the outline of a weapon."
I went to the other side of the frosted glass, positioning my hands as if they held a gun to demonstrate my point.
"What would he do in the precious few seconds before they came into the room? How would he use them if not to cry out?" I moved around the room.
"This little boy, this particular little boy, who reads all of those spy books," I added, seeing them on a shelf. "What would he do?"
"He'd leave a sign?" Lestrade said in a questioning tone.
I started sniffing loudly, as I smelled something. I sniffed around, until I found an empty bottle of linseed oil.
"Get Anderson!" I exclaimed.
A few minutes later, the room was made as dark as possible. Using ultraviolet lights, we could see the message and trails that the boy left for us. The words "help us" were drawn on the wall.
"Linseed oil," I said.
"Not much use. Doesn't lead us to the kidnapper," Anderson said, stupidly.
"Brilliant, Anderson," I said in slight sarcasm.
"Really?" he said, thinking I was serious.
I mentally snorted. As if Anderson could ever be brilliant.
"Yes, brilliant impression of an idiot," I amended.
"The floor," I said, moving on.
"He made a trail for us," John realized.
"The boy was made to walk ahead of them," I deduced.
"On tiptoe?" John asked.
"Indicates anxiety. Gun held to his head." I added. "The girl was pulled beside him, dragged sideways. He had his left arm cradled about her neck."
The trail ended somewhere in the hallway.
"That's the end of it. We don't know where they went from here. Tells us nothing after all," Anderson said, glaring at me.
"You're right, Anderson. Nothing. Except his shoe size, his height, his gait, his walking pace." I countered.
I tore off one of the temporary window coverings, and proceeded to scrape off pieces of the footprints marked with the linseed oil, placing them in a Petri dish.
"Having fun?" John asked as he knelt down next to me.
"Starting to." I said with a chuckle.
"Maybe don't do the smiling. Kidnapped children?" John reminded me.
I just cleared my throat, continuing my task.
A few minutes later, John and I were on our way to Bart's.
"How did he get passed the CCTV? If all the doors were locked..." John began.
"He walked in when they weren't locked." I told him.
"A stranger can't just walk into a school like that," John protested.
"Anyone can walk in anywhere if they pick the right moment." I reminded him. "Yesterday, end of term, parents milling around, chauffeurs, staff. What's one more stranger among that lot?"
"He was waiting for them," I continued. "All he had to do was find a place to hide."
The rest of the ride to Bart's was silent.
***Time skip because I really don't want to go into the details of how he found the factory***
We had just figured out where the kids were. A disused sweet factory called Addlestone.
We raced to the location, jumped out the cars, and ran inside the building.
Donovan split us up, and we began searching.
What we found, we could never have predicted.
I was not in the group that found the three children. Yes, I said em style="box-sizing: border-box;"three /emchildren. A boy, around the age of twelve, was found with Max and Claudette.
The younger boy was unconscious, but the girl and older boy were not.
I also found wrappers. Empty candy wrappers with traces of mercury. Most likely the reason why the boy passed out.
The older boy, by the name of Harry, said that he had been taking a walk, when he saw a man dragging the two kids away. He tried to stop him, but was knocked out. When he came to, he saw the two kids scarfing down the chocolate. He immediately told them to stop, but it was too late, as Max passed out a few minutes later. As he was not strong enough to carry the boy, they had to wait until we found them. He was unable to identify the kidnapper.
As the girl was in shock, I decided to speak to the boy, Harry. I also thought that something was off with the boy's story. Who takes a walk in the middle of the night? In the winter? Something wasn't quite right. However, on my way to speak to the boy, I was stopped by Lastrade.
"These two people came by, said that they know Harry. They want to take him back to where he lives with his relatives before you speak to him."
"Not really interested in their opinion," I said, pushing him aside.
Lestarde, however, stopped me.
"I think that you will find this interesting. Harry was never reported missing."
I stopped in my tracks. That was interesting. The boy had been gone for over twenty-four hours, and no one knew that he was missing? Or did they, and they just didn't care? I turned back to Lestrade.
"What about the people who came to pick him up?"
Lestrade shook his head.
"They said that his relatives had told them that he was missing, and had just come by here to file a report when they discovered that he had already been found."
I frowned. That was very odd. Very odd indeed.
"I need to speak to the boy immediately." I said
Lestrade was able to distract them with paperwork, while I slipped through to speak to the boy, Harry Potter. As soon as I saw him, I knew what was wrong. I was surprised that no one else noticed, especially considering his "choice" of clothing.
I decided to wait until Lastrade returned, however, before I said anything. After going over a few questions with the boy, everything checked out except for the reason why he was outside at such a time and in such cold weather.
"Lestrade," I said as soon as he walked in. "You need to arrest the boy's relatives."
The boy jerked his head up, looking stunned. Lestrade had a similar expression.
"What? Why?" he demanded.
"Because they have been abusing him for at least seven years," I said
The boy stared at me, shocked.
"H-how did you k-know that?" he stuttered.
Two men who I had never seen before, probably the people here to pick up the boy, entered the room. I gave a humorless smirk.
"Well, your clothing choice, for one. It is the middle of December, and you are dressed in what can hardly be called clothes. All short-sleeved, as well. The clothes themselves are at least five years old, and you've had them for four of those years. They are also far too big on you. According to your files, you live with an aunt, and uncle, and a cousin that is about your age. These clothes are probably hand-me-downs. They have clearly not been bought at a second-hand store. There are traces of a name on the shirt. Stores usually don't sell clothes with other people's names on them, and adults don't write their names on their clothes, so, they belonged to your cousin.

Your cousin is the same age that you are, but the clothes are baggy on you. This means that your cousin is overweight, and probably had been for most of his life. His parents dote on him, but not on you. Your clothes have been mended too many times for you to have an obsessive attachment to them, so these must be the only ones that you have, meaning that your aunt does not buy you new ones. However, your cousin only had them for a few months, so she must either buy him whatever he wants, or he grew out of them quickly. Probably both, considering his size. He was probably the one who put holes in the clothes, so that even if the hand-me-downs were relatively new, they wouldn't look very good on you. So he is a part of this too.

However, even if your cousin is overweight, the clothes should not be hanging off you the way that they are. So, you do not get fed often. Certainly not nearly as often as your cousin and uncle are, otherwise you would probably bear a more acceptable weight. Your hands are very calloused. You do a lot of work both in the house and in the flower beds. You sleep in a very small space, probably one of those cabinets that are sometimes put under the stairs for storage, and you are locked in there quite often. You are also not used to sitting on comfortable furniture. Your glasses also get frequently broken. So, knocked, or punched, off of your face a lot. Or stepped on. They are also not the right proscription.

Now, this is where your uncle comes into it. There are traces of bruises and many scars on your upper arms. Now, if the son is overweight, the father probably is too. The bruises on your arms look like they belong to large hands. They are a day old, or so. This happened before the kidnapping, but after it got dark.

Your uncle must have thrown you out that night because you accidentally burned dinner, and then you went on a walk in order to stay warm. You stumble across the kidnapping, tried to help, and got knocked out for your pains. Another tell is that they have not reported you missing, which means that either they did not know that you were missing, or they did not care. Possibly both. Am I wrong?"

There was nothing but silence from the four other people in the room. Harry was staring at me with an open-mouthed expression. The older of the two men who came to pick up Harry looked displeased, but I couldn't tell why. The other man, tall with greasy black hair, looked livid. It took Harry a minute before he could speak.
"Y-yes, that's all right. C-completely right. H-how did you know about the c-cupboard and that I got thrown out b-because of dinner? And how did you know that it h-had been going on f-for so long?" He managed to stammer out.
I gave another humorless smirk.
"The way you hold yourself when you sit, like you try to be smaller. This is more of an instinctual thing, but not completely related to the physical abuse, although that is definitely one of the reasons. There is also a hunch to your shoulders. As for the dinner, there are traces of the type of charcoal that comes from burning food in a skillet. So, you must have been scraping it off when you were thrown out. As for the time frame, the clothes that you are wearing are clearly uncomfortable, but you do not seem to be bothered about it. You are used to them, then.
Also, the chairs in this office are not the most comfortable, yet you have not expressed any signs of discomfort, such as shifting around. You are used to this lifestyle. It hasn't changed for most of your life." I explained. "Oh, one more thing, I noticed that when I was questioning you earlier, you never mentioned your relatives, mentioned that they might be worried about you to be precise. That told me that there was little to no affection between you, enforcing my suspicions that they didn't care that you were missing, if they even knew that you were missing."
Once again, there was nothing but silence.
"Right, then," Lestrade said. "I've heard enough. I'll send some people over to arrest them right away.
"But where will he go if you do?" the older man asked.
I whirled around at them.
"Clearly, if you cared about him at all, if anyone cared about him at all, you would be lining up to take the boy in. In fact-" I cut myself off.
"Wait one moment, Lestrade." I said right before he left.
"What now, Sherlock?" he snapped.
"Arrest this man as well," I said.
They all turned to me, shocked.
"Why?" Lestrade demanded.
"For being an accessory to the abuse. He knew what was going in that house, but he chose to let it happen. He wanted to-no, that's not quite right. There's more. He wanted to both break the boy, and make him desperate. Make him dependent. He wanted to be able to control the boy. I don't know w-oh wait, there it is. You need him for something. Some task that he must accomplish. So far so obvious." I said.

Lestrade, thankfully, didn't waste any time, and immediately arrested the older of the two men, who were both still in shock. The dark-haired man stepped outside the room without a word, leaving me alone with Harry.
"So, what will happen to me now?" he asked, fiddling with his fingers nervously.
I smiled.
"I think that dark-haired man is thinking about it," I said.
Harry shook his head in disbelief.
"Snape? He hates me. Why would he help me?" he asked.
I grinned.
"Hated you, I think. If I read the situation right, then he had a similar experience to yours. He is especially sensitive to abuse cases."
Harry still looked like he didn't believe me, but didn't respond.
At the end of the day, Harry's relatives were arrested. The older man was also arrested.
And to Harry's surprise, the other man apparently named Severus Snape ended up taking Harry home, and adopted him permanently within a month of the event. All in all, an interesting case solved.

I hope that y'all enjoy this! I think that if Sherlock ever met Harry, he would have been able to easily deduce what was going on at the Dursley's. I personally really enjoyed righting the part where he deduced Harry and Dumbledore. Dumbledore was the "older man," by the way.

Soundwave's Wife❤️