A/N: So, here's a little story for you all. Basic premise; I squashed the timelines somehow so that BBC Sherlock exists at the same time as Harry Potter. Sherlock and Snape are cousins. And my John may be a bit OOC. Enjoy yourself and cheer yourself with the fact that I also do not own Harry Potter and BBC Sherlock. Just like all you poor souls out there. (Unless your JK Rowling or Moffat and Gatiss, then all I have to say is, 'You wonderful and amazing person, you.'

Last note, there are multiple POVs in my story, and they tend to slightly overlap each other.


It had been a normal day.

No, more than that, it had been one of the nice normal days. And Harry doesn't mean an out-doorsy nice day. Nope, the weather was rubbish. Not a singing bird or a ray of sunshine in sight. Instead it was a soggy, wet day with a wind that sought to flatten anything in its path.

The nice day began when he woke up without any echoes of Voldemort's latest tantrum thrumming through his blood. Then there was the added fact that no one seemed to be set on killing him today. Not even Umbridge, who had apparently come down with some-sort-of-illness-that-Harry-had-ignored-because-he-really-didn't-care. It might have been dragon pox or the licking flu for all he cared.

In the end, all that mattered was that the toad would be unable to teach and until they found a willing witch or wizard to take over for her, they would have a free period. (Personally Harry blamed Fred and George for the last minute sickness, just in time to give Harry a break from the toad. Thank Merlin.)

Yes, all in all, it was turning out to be one of those good days that were as rare as a toothless dragon.

Sadly, whatever Umbridge had didn't seem to be catching and he still had to go to Potions.

As he, Ron, and Hermione trudged downstairs, Harry found himself fiercely, desperately wishing that his luck would hold out and that he would make his way through Potions and the infuriating bat of the dungeons without incident.

Harry honestly should have known it was too much to hope for. At least he didn't get a detention.

"Potter!"

Harry looked up from inspecting his potion and his fiercely whispered conversation with Ron. The bubbling liquid inside his cauldron was supposed to be a colour that the book referred to as 'puce'. The only problem was, both Harry and Ron had no idea what colour puce was. Instead it had turned a vicious red. Sometimes, he didn't know why they tried.

"Yes, Professor?" He asked, the question coming out sharper than intended as a result of his prior conversation. The Potions Master was glaring at him from his long, and frankly ugly, nose and Harry felt a moment of relief that he had grown considerably since his first year. The amount that Snape was able to look down upon him was now remarkably smaller.

"There are some people here who actually intend to be successful," The man sneered, "it would behoove you to not deny them that privilege, even if you do not have such high aspirations for yourself. That is, if they can even manage to brew a potion properly. So please, be quiet."

Harry glared, the hatred that he felt for this man rising to the surface. But he gritted his teeth and replied with a reluctant, "Yes, sir."

All he had been doing was discussing the technique of this particular potion with Ron.

Alright, so perhaps they had been arguing. But it was over who was going to remove the fresh newt eyes from one of the live newts that were crawling over each other in a large tank. Snape could hardly punish him for being off-task. But no more words were spoken and Snape, with a withering glare, swept away to criticize someone else. Oh wait, that was a Slytherin. Not criticize. Ron watched the professor, his face pinched with dislike. Then, with a look that clearly said, 'You owe me, mate' walked over to the open ingredients cupboard and quickly stunned and grabbed one of the brightly colored lizards out of their tank. Apparently, Ron had decided that he had lost the argument and Harry wouldn't have to dissect a lizard's face.

There was silence as the class worked; no one was willing to incur the wrath of their professor. The only sound to be heard was the sound of chopping knives and boiling cauldrons and the scattered sniffles and coughs caused by the moldy dungeons made humid by their steaming cauldrons. At least it was warmer than the upper levels of the castle. They were nearly impossible to keep warm. Even with magic.

This rare silence lasted all of five minutes, when, from somewhere beyond the potions room, there came a crash and several curses. Then there was another voice, one not swearing, this one a deep timbre that was entirely too calm. Finally, above the intelligible murmurs came a panicked, "What was that, Sherlock?"

Everyone was alert, their attention on the door that the voice had emerged from. The only thing to shift their attention was Snape as he strode to the door tucked into the corner of the room, his face unusually and unnaturally red. Before he managed to reach it, it slammed open, revealing a tall, dark and sharply dressed man who was in the middle of speaking.

"Come along, John." A tired sigh, "Oh, don't be like that, it's for the case! Don't worry about it; it's just a bit of magic. Ah, Severus, just the man I wanted to talk to. Tell me, is there a voodoo trick, or whatever it is that you do, that doesn't leave any sort of physical trace and can be used to murder someone?"

It was clear to the students as the stranger strode towards their professor that he knew Snape, but it looked like it wasn't a friendly acquaintanceship. It was also clear to them, as it would be to any sensible person, that anyone asking about killing spells was up to no good.

Snape's face was an uncomplimentary shade of blotched scarlet — however most would say that any color was uncomplimentary on the foul tempered man — and he seemed to be barely holding in a rage that all in Hogwarts knew tended to be explosive.

"What are you doing here, Holmes?" Snape said, the words hissing between his teeth like steam from a simmering potion.

"Don't be so dull, you surely must have heard me talking to John. And even if you are indeed as deaf as you appear, it must be obvious. Why else would I be here—a case!"

There was not a single face in the potions room that did not express shock — although some with more glee or indignation than others — at the gall of the stranger, Holmes, Snape had called him, to insult their professor like he did. Not with rebellion, or stubbornness as the bolder students had (in this case Harry), but rather as if, instead of insulting Snape, he was describing him.

Their awe continued as Snape did not retaliate, but instead pressed a different concern. One that Hermione would soon realize was a much more pressing one.

"Who came with you, Holmes?" Snape's tone had lost none of its bite.

Holmes just flapped a hand in Snape's direction, uncaring. "Don't worry, it's just my friend, John. He's completely competent, he's the last person you have to concern yourself over spilling your huge secret. Well, I say completely, but really he's just the best in a bad lot. But I trust him implicitly, so there's no need to be concerned.

"In fact I'd be willing to bet that tomorrow morning he'll just accuse me of drugging him. Such an awful habit of his, I don't know where he gets it from. I've only drugged him once, although I have some plans for an upcoming Wednesday." The erratic man appeared to notice what he was actually saying. "Er… probably best that you don't mention that last bit. Now. I have some questions about spells. Are there any-"

As if on cue, and confirming Hermione's growing suspicions, a plain, well-built man came stumbling through the same doors that Holmes had, cursing. The only coherent thing that could be made out was,

"What just happened, Sherlock?!"

And Hermione, as was her want when she finally figured out a puzzle let out a gasp. But also as was her want, she found herself unable to keep what she had figured out to herself.

"You're a muggle!"

So focused the new man must have been on his companion that it seemed he had only now realized the presence of the teens filling the room. More than just that, the bright witch's exclamation broke the spell of silence that had covered the class. Not a literal spell, fortunately. All at once each of the students began talking to and over each other, creating immediate chaos.

"A muggle? Here in Hogwarts?"

"Sherlock…Holmes? I think I've heard of him. Mum talks about him a lot. I think he's in the papers."

"What are we supposed to do? Where's Dumbledore?"

"How does Professor Snape know him?"

"Just wait until my father learns about this!"

"He dresses funny, but he's kind of cute. In a weird way."

"Merlin! Fred and George will love this!"

"SILENCE!"

The students fell silent, more because of the threatening weight of Snape's glare than because of the deafening shout.

"Holmes, for the last time, I ask you to leave. If you do not, I will forcibly remove you myself. And I assure you, I will enjoy it immensely."


Now, under no circumstances would John classify this day under the title of good. He had been woken at three in the morning by his insane flatmate insisting that they go on a road trip. "For a case." He had said. This declaration did not make for a happy John Watson. It wasn't that he didn't believe the man. Oh no, it was all too easy to believe that Sherlock would be waking him up before it was reasonable to even call it morning, no matter what the clock said, for a cold case.

Yep. A cold case.

One that the Yard had apparently shoved to the side, unsolved, years and years ago. When Sherlock had found out about it, he had been a force to be reckoned with; stealing files from the Yard and harassing Lestrade and his brother, and pacing long and hard enough to gouge an even deeper groove into the floor of the sitting room than what was there from preceding cases.

To be honest, John hadn't expected too much to come from it. Aside from a moody Sherlock that is. And no matter how awful a moody Sherlock was, such a state was all too common for John to become too concerned. That is, until he awoke to Sherlock tearing his covers from atop of him at four in the morning.

A good day, indeed.

After the unpleasant morning call, things didn't improve any. First there was the drive vaguely northwards that John had tried to sleep through. As able as he was to fall asleep in a variety of places and situations, a car was not one of them, and John would doze off only jerk awake moments later to find another position to sleep in. As to where Sherlock had gotten the car, John preferred not to speculate. And when it had become obvious that his brain had firmly decided that it was time for him to wake up and stay awake, John sat in silence. For once wishing that he had wasted some money on one of those games you could play on your mobile. Mind-numbing entertainment had actually sounded pretty good right then..

Then, when they had arrived in the village that was their destination, Sherlock came to the realization that he apparently had deleted the address, despite the obvious importance of such a detail. This realization had come several hours too late to do anything about it, much to John's annoyance. They had then loitered around a sad little park for hours with Sherlock alternately scouring his mind palace and John insisting he either ask for directions or call his brother. Of course, Sherlock refused to do either.

Finally, John, tired and grouchy, decided to call Mycroft himself. He couldn't very well ask for directions seeing as Sherlock had refused to say anything on the matter and he didn't know where to ask directions to, so the only option was Mycroft.

Predictably, it was just as Mycroft answered his mobile (John will be always grateful that he had been given Mycroft's personal number and not his office or assistant's number) that Sherlock finally figured out where to go. Embarrassed and frustrated, John apologized profusely for disrupting the elder Holmes brother's running of the government and hung up and followed Sherlock.

They were walking along a road that gave the appearance that whoever lived there was either evil or desperate. (Well, not walking per se, Sherlock was closer to striding, which forced John to keep up with him with the little half-run thing that made him feel remarkably ridiculous.) Now, John wasn't one to form opinions based on appearances and the people who lived here surely had their own lives and story. However, John was not above judging a road. And this road was just plain depressing.

"He should be gone, so we won't have too much trouble." Sherlock said conversationally as they turned down another road.

"What?"

"The man who lives here; he's a teacher for a school somewhere. It doesn't matter. Anyways, teacher. It's early November, so he'll be at the school. Luckily, I still remember our many conversations. We'll just go into his house and make a quick visit."

Making no sense, check. Being deliberately vague, check. Breaking into someone's house, che- wait.

"We're breaking into some guy's house? Again? Sherlock, it's way too early for this. Let's get a hotel and come back tomorrow."

"It's hardly early John, it's already eleven."

"Yes, that means I've been up for eight hours. And that means that no matter how much you want to, I am too tired to go breaking into houses for the sake of a cold case."

"Oh come on John, it will be exciting! And besides, you needn't worry so much about the consequences. The house that we will be breaking into belongs to my cousin."

"Your cousin?" John was dubious, not that he entirely doubted that Sherlock was telling the truth. However, it remained that John knew very little about Sherlock's family and there was no way to know if Sherlock was just telling him what he thought John wanted to hear for the sake of the case. Alright, so he supposed that it was that he doubted the word of his friend, but in his defense, John never was in the best of tempers or the most forgiving when tired. Not to mention, Sherlock wasn't the most forthcoming or honest when it was a case on the line.

"Yes. I haven't seen him since I was a teen. Easily twenty years ago. However, I recall that he had a unique skill set that could prove to be very beneficial to my investigation. Perhaps even more investigations if all goes well."

John shot Sherlock a look, not that the man could see it and sped up his pace, forfeiting dignity for answers. "And what exactly does this cousin of yours know that you have deemed unnecessary in that mind palace of yours, but apparently has the ability to solve several cases."

Sherlock stopped his furious pace and turned to John causing John to nearly run into him. John looked up at his friend confused, taking in the mad glint that shone through his eyes and felt a bit of apprehension.

"Magic, John." And he was off again.

With a sigh, John started after the taller man, muttering, "Alright then, if you don't want to tell me…"

It was a very short while later that Sherlock stopped in front of a house. However, looking at it, John felt certain that it was the wrong house. It didn't look any more or less sad and desolate than the other buildings lining the street, but John couldn't help the nagging feeling that he shouldn't be there. Surely he had forgotten something important back at the flat. Had he turned the stove off? Hadn't Sarah wanted to meet up this afternoon, he should really give her a call.

But why was Sherlock stopping? They were looking for his cousin's house and this couldn't be it. Any relation of Sherlock just had to live in a mansion of some short. At the very least not this dump.

"Sherlock? Why did you stop? It's probably further ahead."

Sherlock glanced at him. "No, this is it."

"Are you sure?" Because John knew that this wasn't right.

Something he'd said must have triggered something in Sherlock because the next thing John knew, the other man was beside him.

"John, look at me." He pulled his gaze away from where he was looking down the pavement to do as Sherlock asked. Once he did, Sherlock firmly placed his hands on either side of his head. "Ignore it. This is the right house. I know. I've been here before. Trust me okay? You do trust me, don't you?" John nodded, despite the fact that he was being very obviously manipulated. "Good. Now, ignore whatever is telling you to stay away from this house and follow me. Okay?"

John's mouth seemed to move of its own accord and, despite how his entire being wanted to go away from this house, replied, "Okay."

At that, Sherlock turned and darted up to the front door.

And John somehow found it within himself to follow.