Disclaimer: I do not own Harry Potter nor do I own Sherlock Holmes.
The door of the compartment slid open and a dark haired boy came in. He did not so much as look at Harry—much less utter a word—before letting his body fall against his seat, putting his arms behind his head and seemingly falling asleep.
Harry could not see the face of the boy clearly enough, as his hat covered most of his face. From his height, Harry figured he should be a first year like himself. He wondered why the boy wore wizard robes instead of changing while on the train, and found himself voicing that question.
"Were we supposed to be wearing our robes before we got on the train?" Harry asked, regretting his question as soon as it had been asked. He feared waking somebody up would not make a good first impression.
"I don't think so." The boy spoke without making a single movement, not even shifting his hat to look at Harry. Harry wondered if he was just pretending to be asleep to avoid talking and regretted opening his mouth even more so than before. But before his regret could catch up with his brain, he found himself asking, "Then why are you wearing a robe?"
"Because it's more practical. That way I don't have to change in the train."
"But don't Muggles get suspicious when they see someone in robes like that?"
The boy sneered and though Harry couldn't see his face, he caught glimpse of a smirk the hat just barely failed to hide. "Do you know what people do when they see something that strikes them as unusual and with no reasonable explanation?"
Harry shook his head.
"Nothing at all," said the boy cheerfully. "They do nothing at all."
"Did you use magic?" asked Harry.
The boy didn't reply immediately, which Harry took as a sign of surprise.
"I mean, you can't see my face right? Your hat is covering your eyes," said Harry. "But you still knew I had shaken my head. So that's why I'm asking if you used magic." Harry felt dumb for asking what could be an obvious question, but his curiosity was stronger than his fear of sounding stupid.
"I don't need magic to read minds," the other boy responded calmly.
"And thanks to that, we had a very productive term last year, isn't that right Fred?"
"Indeed we had."
The twins who had helped Harry were back.
"I see you have met our friend Harry," said one of the twins, "he acts like a bit pain in the butt, but if you give him a chance and see through that mask, you'll see that he's actually a huge pain in the butt."
"One we are thankful for having," said the other twin in a heroic tone, looking at an imaginary sunset in the train. "I don't believe we have introduced ourselves last time. We are George and Fred Weasley. If you don't know which one of us is which, feel free to call us Gred and Forge." He then shifted his head towards the boy who was still pretending to be asleep. "And this fine gentleman about to regret ignoring you once he finds out who you are is—"
"I'm not going to regret anything because I already know it." The boy spoke not with anger, but with something Harry thought was mild annoyance. "He's Harry Potter."
"How did you—"began Harry, before being interrupted.
"Harry Potter would be eligible to enter Hogwarts this year, judging from his age. You were unsure about attracting attention from Muggles, which meant you weren't sure how the magic world functioned. But despite that you have a lot of wizard money—I can tell by the sound your pockets make—which makes it unlikely for you to be Muggle-born, given how little Muggle money is worth these days when exchanging wizard money plus the limits they place on how much money you can exchange per month. That meant you had to have inherited money from a magical background while being raised by Muggles your entire life. No wealthy pure-blooded or mixed orphans are supposed to enter Hogwarts this year besides Harry Potter as far as my brother's painfully accurate information network says. So you are Harry Potter." The boy spoke rapidly, but without stumbling. His facts were precise and simple, to the point where his logic seemed obvious once explained.
"You got all that," Harry repeated incredulously, "from the sound my pockets made?"
"That's him all right," said one of the twins chuckling. "We would love to stay and explain how his mind works, but Lee Jordan has got a tarantula that we need to see. See ya later."
"Bye," said Harry. The twins slid the compartment door shut behind them.
Harry couldn't stop himself from asking, "Who are you?"
The boy smirked once more, and got up with one swift movement. Taking off his hat, Harry took note of his pale face, his condescending yet distinctively kind smirk, and most strikingly of it all, the sheer amount of confidence displayed in every feature of his expression. It wasn't the arrogance Dudley so often displayed. It was different.
"Holmes," he said proudly. "Sherlock Holmes."
"Are you from a family of wizards?" asked Harry.
Seeing that Sherlock would not volunteer any information about himself so easily, Harry decided to pursue it more thoroughly. It occurred to him that maybe if he talked about himself a bit, Sherlock would follow him. "I don't know what living with wizards is like, but it must be better than living with Muggles. Well, at least the Muggles I lived with. They hated me. They hated magic and anything abnormal, to be honest. I—"
"If they really hated you," said Sherlock. "You probably wouldn't have noticed. Hatred is not a particularly dramatic emotion. They must have liked you to some degree, which is why they hated you."
"I'm sorry?" Harry asked, confused. He was pretty sure the Dursleys hated him.
"You just said it," said Sherlock, with a tone of someone who explains the obvious. "They hated magic. So they hated you for being connected to magic. If they truly hated you , they wouldn't have raised you."
"Isn't it the same thing in the end?"
Sherlock shook his head. "Acts and motivations are two different things, and they both matter a lot."
The shameful looking boy Harry had passed by a few minutes before came into their cabin following a short, depressing knock. He looked as though the world had given up on him.
"Sorry, he said, "but have you seen a toad at all?"
"Is that how you start all conversations?" asked Sherlock.
"He'll turn up," said Harry.
"And if not," said Sherlock gesturing at small markings on the ground. "Just follow his little wet toad trail. It's not too hard to see if you pay attention to it."
"How could I have not seen that before?" said Neville, sounding more disappointed at himself than happy at the prospect of finding his toad.
"How could anyone have seen it?" asked Harry, dumbfounded.
"We all saw it. You just didn't observe it."
"Is there a difference?" asked Harry confused.
Sherlock's grumble and lack of an answer indicated that yes, there was a difference and he was very much annoyed Harry didn't understand it. Neville thanked Harry, perhaps afraid of thanking Sherlock, for the hint, and went off to find his toad.
Neither of the boys spoke for a while. Harry bought a little of each candy not wanting to miss out on any, and had a mixture of fun and suffering as he ate them. He tried offering a few to Sherlock, but he was still clamming up from earlier and refused to say a word.
Later, when the silence was slowly but surely becoming unbearable and Harry found himself really wanting to have someone to talk to, a knock on the door gave him his wishes in the form of a first-year girl, also wearing her Hogwarts robes.
"Has anyone seen a toad? Neville went out of the cabin to look for his and hasn't come back yet."
"Yes—well no, but we saw Neville. We told him to follow the toad's trail. It's hard to see, but it's there," said Harry, but the girl wasn't listening. She was staring at the pile of candy wraps sitting beside Harry with an unbelieving look on her face, as if she couldn't understand how a person could make such a big mess by himself.
"I'm sorry," Harry apologized. "I ended up buying more than I could eat. Would you like some?"
"Well," she hesitated, "Neville is still looking for his Toad right?"
Harry nodded. "He knows how to find him now."
"Then I suppose it wouldn't be a problem to stay here for a while," she said as she sat beside Harry. "I'm Hermione Granger."
"I'm Harry Potter, and he is Sherlock Holmes."
"Are you really?" said Hermione. "I know all about you, of course—I got a few extra books for background reading, and you're in many of them!"
"Am I?" said Harry, unsure whether she was serious or not.
"Yes you are," said Sherlock, breaking his vow of silence. "I suppose I should thank you for getting rid of Voldemort. That was nice of you."
"I thought people normally didn't say his name out loud," said Hermione. "Did I make a mistake?" Hermione seemed really anxious about having made a mistake.
As far as Harry could tell, she hadn't made a mistake and he informed her as much. It felt nice to share the feeling of not understanding how the world was supposed to work with someone.
"Normally, people with a magical background don't say his name," said Sherlock, "you are correct."
"But you just said it," said Hermione. "Don't you have a magical background? I have read the name Holmes before as well. Your father—"
"Yes, I have a magical background."
"But you just said it," Hermione repeated, growing annoyed at him.
Sherlock raised an eyebrow at her, apparently not understanding what she was having difficulty with.
"Yes, people don't normally do what I do. What's your point?"
Before she could make her point known, there was one more knock at the door and this time it was not about a toad, but about Harry. Three boys came in, and Harry knew who one of them was at once. It was the particularly vicious boy he had met at the Diagon Alley. It seemed as if he intended on asking a question about Harry, as he looked at him for a few seconds and managed to get out a few syllables before cutting himself short.
The reason for the boy's change of plans seemed to be that he had seen something that shocked him far more than Harry's presence, and that something was waving at him with a sadistic smile on his face.
"Hello Draco Malfoy!" said Sherlock. "It's been almost a month! How did that dinner go once I left?"
Draco instantly adopted an expression of both disgust and shock. Then, with great effort, he turned to Harry.
"If you aren't careful about the people you are with, you will end up just like your parents." He shot Sherlock a disgusted look. "Or worse. Much worse. "
The three boys immediately left the cabin, leaving behind a very confused Hermione and a very confused Harry, who both looked at Sherlock awaiting an explanation and then at each other once it became clear no explanation would be given.
"Not very pleasant, those three," said Harry.
"I heard they were no good before but I wasn't expecting that," said Hermione. "But fortunately Sherlock's presence seems to have been enough to make them run away."
"Yes, I have that effect on scum," Sherlock agreed in a solemn tone that contradicted his mocking words. Harry wasn't sure if he was joking or simply stating the matter as he saw."The Malfoy family has been linked with Voldemort before, famously think that pure-blooded wizards are better than all others and most importantly, I don't like them. So stay away from them."
"No need to say it twice," said Harry.
"The train should be arriving at Hogwarts soon," noted Sherlock. "So I'd advise you to leave while Harry here gets changed, unless you want to stay for that."
Hermione blushed, then quickly turned around to leave the cabin.
"I don't think you had to be rude to her," said Harry. He didn't particularly like the way he treated her and he wasn't sure he liked Sherlock's attitude in general either.
"I don't think I had to be rude either," Sherlock agreed cheerfully.
At that moment, it came to Harry that Sherlock Holmes was quite simply not a reasonable person. He wasn't like Dudley, who had been spoiled to the point of not knowing the difference between right and wrong. He was someone who knew fully well the difference between right and wrong, someone who understood how social norms were supposed to play out and above all he was someone who simply did not care for any of that. He was insane.
Due to a long list of reasons that would take a really, really long time to explain, Ron Weasley does not exist for the purposes of this story, as Sherlock has been inserted in a way to "replace" him.