John discovered all over again when he'd known all long: the most dangerous Sherlock Holmes was a bored Sherlock Holmes, but the second most dangerous Sherlock Holmes was an entertained Sherlock Holmes. Four days passed before Sherlock started to really experiment with magic. John considered himself lucky Sherlock had waited that long.

The amount of time probably had to do with the fact that Sherlock had approximately a mountain of books to read, which even Sherlock Holmes at his lightening pace couldn't absorb in only one day. Even John spent a significant amount of time with his nose buried in a book. He'd drag his wizard fiction to work with him to read between patients, and stayed up late reading every night anyway.

The amount of time between Sherlock finding out about magic and his first experiment corresponded directly to the fact that Sherlock latched onto Arithmancy and Ancient Runes first. When John finally figured out exactly what Arithmancy was he was almost shocked at how Sherlock took to it, until Sherlock had vaguely explained it.

"It's hardly magical, John. It's similar to the process of creating insurance charts. With a large enough sample you can predict anything if you use the proper algorithm," Sherlock had said. John had a feeling that he could get it if he studied it for years. It took Sherlock no more than a day to memorize the complex charts, algorithms, and systems necessary for the study. He then promptly forgot most of it, deciding that it would have little practical use. Even if it was necessary, he remembered the parts it would take to re-figure out the rest.

Runes took approximately as much time for Sherlock to memorize them. Even John could see that it was basically a theoretical study. Sherlock seemed to deem it very important as John still found him looking at Runes on the fourth day.

The third day was devoted to the topics Sherlock seemed to actually care about. John saw Sherlock looking through various Muggle study books until Sherlock finally let out a loud sound of disgust and made the effort to get up and hand John a book titled Home and Social Habits of British Muggles. "Fix it, John," was all Sherlock said.

John didn't go to work that day, too busy going through the book and changing anything that was preposterous. Often John found himself staring at the page in shock of the sheer stupidity of what he was reading. Did wizards think muggles were a type of alien? Because that was the only way John could make sense of the terribly stupid mistakes the book made on trying to analyze the muggle thought process.

Sherlock retreated into Herbology and Potions text after that.

All in all, John felt lucky that Sherlock had waited four days. He felt lucky that The Monster Book of Monsters kept Sherlock interested not just in the contents but in the book's ability to move on its own, and that Wordsworth the Puffskein would coo happily when Sherlock hurled him against the wall as he thought. John felt lucky that Sherlock actually seemed to think before he attempted a spell.

Still after the fourth morning when John had to call the newly installed phone at the Leaky Cauldron, and to shout at Neville to come with fix the large amount of purple billowing steam filling the apartment, John was more than a little frustrated that Neville hadn't come sooner to work with Sherlock.

"It's not like I'm not trying," Neville said after cleaning up Sherlock's mess with the flick of the wand. John was frankly jealous of that ability, especially since they couldn't open the windows and risk the neighbors seeing thick purple smoke.

"How hard is to come supervise?" John snapped.

"I'm hardly the one to do it," Neville said. "What part of barely passed Potions as a subject when I was in school did you not get before? I'm trying to get someone actually competent to come."

"Then how hard is to call someone?" John asked. Normally he wouldn't jump on such accusations of incompetency, but he'd been faced with complete uselessness. There was nothing he could to clean up Sherlock's mess this time except call someone else.

"It's very hard when the man in question doesn't have a phone. I sent him a letter by owl post and just got it back. I'm going to see him tomorrow and try to get him to come by," Neville said. He clearly was on edge as well. "Do you think you can hold him off until tomorrow?" he asked, looking at Sherlock who was sulking like a kid whose favorite game had been taken from him.

"Easier said than done," John muttered. "Sherlock, Lestrade called earlier with a case."

"It's a three, I distinctly told you I won't leave the house for any more than a six," Sherlock said.

"Then what about your blog. You've got clients or puzzles on there you can look at," John said. "Or hell, you bought like fifty muggle studies books, why not look at those?"

"Because you're moronic, John," Sherlock said. "I gave you the best one already."

"Which one?" Neville asked.

"Home and Social Habits of British Muggles," John said.

"Ah," Neville said. "Hmm… is that one bad?" he asked.

"I'm working on it," John said.

"It may be poorly written with many grammar errors, but it will at least be correct," Sherlock said.

"I'm working on it," John reiterated.

Neville left them after that, and John was left to keep Sherlock distracted. It didn't prove to be that hard. Sherlock did have correspondents to work on. He had only three that he felt marginally interesting enough to send response to, but otherwise he found them dull. John let him experiment a bit on Wordsworth, mostly looking at the hair and running a small blood sample. Wordsworth didn't seem to like Sherlock as much after getting his blood drawn. John had to pet and soothe him after that.

John was happy when Mrs. Hudson called up the stairs in the morning that they had visitors. John couldn't miss another day of work, especially because he wasn't even going to be there for a month. Mycroft would keep him from being fired, but John needed to be able to pay rent at some point. The army pension could only get him so far.

"We're having breakfast if you're interested," John said when the footsteps on the stairs got close enough. Well, he was having breakfast. He'd managed to get Sherlock to have an egg and a piece of toast, but John felt content in that.

"Anything better than normal bachelor's fair?" a man asked. John turned around to see the aging, round man come in behind Neville.

"Not really," John said, standing up. "John Watson."

"Horace Slughorn," the man said, shaking the hand John offered, but his eyes slid past John to Sherlock. "And you must be Sherlock Holmes," the man said.

"Potions teacher, well over sixty years of tenure, though with a retirement in between. Fought in the same battle Longbottom did about 13 years ago. You like luxury, live with it even though you can't afford it on a teacher's salary, which means that most of it comes from gifts, most likely from people you've influenced in the past," Sherlock said after giving the man a glance.

"Well, you are as a good as they say," Slughorn said. "Well, to work then," he said, clearing the table with the flick of his hand. Both John and Sherlock's eyes went wide, neither of them having seen anyone perform wandless magic before.

John went and got dressed for the day, looking into the kitchen to see Sherlock and Slughorn with their heads together over the cauldron as he headed out. When he returned home that evening Slughorn was still there, working with Sherlock on something that John decided not to ask too much about.

Slughorn became a very normal part of their lives after that. It wasn't just Sherlock who was interested in Herbology and Potions. John would often get involved when it came to healing potions. John quickly discovered that he enjoyed potions. There was something very soothing about it. You follow the instructions and you get something that could heal aches and pains or bone fractures, or even regrow bones. Both John and Sherlock had been very interested in getting the story of Harry Potter having to have all of the bones in his arm regrown out of Neville when he came to visit.

Three weeks passed like nothing for John, and the next thing he knew he and Sherlock were back to their old lives, with no Neville or Slughorn around to entertain them with stories about Hogwarts, or answer questions about the Dark Arts, or to help them with their continued crash course in potions. Neville gave John an emergency contact number in case one of Sherlock's potions experiments went awry.

"I'll see you both in Tweleve days," Neville said upon their last meeting.

"Tweleve days is a long time," John mused once Neville had gone. "Enough time for a case or something," he said a bit hopefully. He didn't know how else he was going to keep himself and Sherlock from climbing the walls otherwise. Eleven days between them and the chance to explore a magical castle.

Neville couldn't have been happier to get back to school at the start of term. Of course he was sorry to leave his girls behind, but he'd see them on weekends. Mostly he was just happy for the temporary respite from Sherlock Holmes. Neville had decided that he didn't dislike Sherlock, but he'd also decided that John Watson was a real hero for putting up with Sherlock Holmes all day every day. There was only so much Sherlock a human being could put up with, and Neville had been on call for Holmes Watch the entire end of the summer.

Professors arrived a day early to finalize lesson plans, meet the new staff and get all the announcements out of the way. They all needed to be on the same footing for when the term started. August 31st was all about business. That being said, that didn't mean that there wasn't plenty of gossip.

"Neville, is it true that you've been tutoring muggles this summer?" Septima asked with a secretive smile.

"I'd hardly call it tutoring," Neville said.

"Horace has been bragging on about how this muggle is one of the best pupils he's ever had," Bathsheba whispered like it was a big secret.

"I think he may have covered three years or more of potions in three weeks," Neville admitted. His two coworkers looked stunned.

"Talking about the muggle," Filius Flitwick said, coming into the staff room in time to hear the end of the conversation.

"Yes," Neville said. He had a feeling that he wouldn't be escaping Sherlock even when away from the man.

"As good as Horace says?" Filius asked.

"And probably just as much trouble as the Weasley twins were, combined," Neville said with a tired smile as the rest of the staff entered and took their seats. Helen Proudfoot took her usual seat next to Neville, who was closer to her age than the rest of their peers, but she was still a good 11 years older than him. Still, she had been an Auror until she retired after Voldemort fell, and took up the position of Defense Against the Dark Arts. She was serviceable, but Neville still occasionally wished that Harry would come teach. No one taught Defense like Harry could.

"Now," Pomona said, getting everyone's attention. "First order of business is to introduce to you our new Muggle Studies professor, Morgan Burbank." Neville had seen the woman and really, truly hoped that she wasn't who Neville thought she was. He politely clapped like the rest of them, but inwardly he was shuttering.

It seemed that they hadn't found anyone suitable by the deadline, because Morgan Burbank was clearly sent by the ministry. It wasn't that the anti-muggle sentiment was still very strong per say, but there were many witches and wizards who thought of muggles as quaint, as if they were defective people who could not have magic. These people would stand up and scream about muggle rights and how we had to protect the muggle way of life for their own good, and yet never saw muggles as people, only as a cause. Morgan Burbank was clearly one of those people. She was just terrible wizard and she had that dreamy type of smile to her that was too saccharine to mean that she cared about teaching students about muggles as anything more than a lesser species.

"Onto the second bit of business," Pomona said once the newly introduced chatter settled down. "As I'm sure most of you are aware already, we will be having guests through part of September and October. Misters Sherlock Holmes and John Watson will be observing classes and students during their stay here."

"The muggles," Thaddeus Lowry, the current transfiguration teacher said.

"We have agreed in hopes of improving muggle-wizard relations," Pomona said. Still, the rest of the group exploded into chatter once more. Neville grit his teeth and hoped this wouldn't be too much of an uphill battle.

"I'm not quite sure I understand," Aurora Sinistra's voice finally rose over the others. "Why exactly are we allowing muggles into Hogwarts, especially ones who have no relation to students."

"No, it's good," Morgan Burbank said. "It will be a good way to gauge muggle reaction to the wizarding world," she said. "I'm sure they will be quiet awed by what we have to offer," she added.

Neville tried to think of Sherlock Holmes being awed. Excited? Oh yeah, the man could reach that. Awe was something for lesser mortals, though. And while John Watson might awe at something, he doubted it would last too long.

"What I do not understand is why we are allowing the Statute of Secrecy to be broken," Aurora continued. Well, she had a good point.

"It's precisely to do the opposite," Slughorn said. "I tell you Aurora, Sherlock Holmes is one of the smartest men I've ever met, we allow a man like that to his own devices and he will blow the Statute of Secrecy completely."

"Then why are we allowing him in?" Thaddeus asked. "Why not obliviate him?"

"That wouldn't work," Neville said. "We could erase those parts of his memory and he'd notice that he's missing parts of his memory and go twice as hard to discover why, and this time he'd have no reason to keep our secrets. Trust me when I say this isn't a man we want to anger."

"No one can be that good, surely," Morgan Burbank said. Neville wondered if she meant no one, or no one muggle.

"He can," Neville said. "He can tell you your life story at a glance, he did it to me an Horace, and Harry Potter."

"Is there a possibility that he's magic, or charmed in some way?" Filius asked curiously.

"No," Slughorn said. "He's as muggle as they come."

"What is important," Pomona cut across the noise. "Is that he is a very capable investigator. I have been assured by the Auror department, and sources within the Ministry that Mister Holmes has been instrumental in solving some very high profile cases that the normal muggle police were unable to," she said.

"I wouldn't think that would be hard," Helen Proudfoot said.

"Not the magical cases," Neville added. "I read the cases John wrote up on his blog," he said. He noticed instantly the confused and vacant stares from his coworkers. "Blogs are like a self-published newletter that muggles created for the computer, and they're distributed instantly as soon as a new story is written."

"That doesn't seem that useful. How can you know what's good and what isn't?" Septima asked.

"Sometimes they aren't, but blogs allow for a greater amount of information to get out. Anyway, John Watson, Sherlock's partner writes their cases. They're very fascinating, in fact they're apparently quiet popular with the muggles."

"I did read a few," Slughorn added. "Quite remarkable. I'll see if John will print a few and send them along."

"If I may," Pomona asked, glad that the professors seemed to have calmed down on their own, and settled the arguments a bit on their own already. "I have been told that Mister Holmes may consult with the Auror office in the future, and they want him to have ready access to and understanding of our world. If he is as good as I have been led to believe he may be a valuable resource in catching perpetrators of the Dark Arts. We are being asked to do our duty," she said. That got everyone's attention. "And help Mister Holmes have a full understanding of our world."

"When will he observe our classes?" Morgan Burbank asked.

"Over time. He, and John Watson will be here for a month, and I have been told that they was done research on most subjects. I ask that you treat them with respect and offer to them your best resources. At the very worst these men will pose for the students as a formative memory of muggles and how they think of and treat wizards. And how we react to them will also affect how they see muggle-wizard relationships."

Neville nearly groaned. John Watson was a good man, upstanding, strong of will and heart. He was Gryffindor through and through. Sherlock was a Ravenclaw at best, Slytherin at worst, except that Sherlock seemed to have little true ambition except to not be bored. Still, Sherlock was one of the most caustic individuals Neville had ever met. The only people Neville considered more likely to insult students and staff alike were the Carrows. Neville wasn't even sure if Sherlock would have been as back as Snape. Surely Snape couldn't have been as bad as Neville's memories of him. Even still, Neville had trouble not associating Sherlock with Snape, which made their discussions less than comfortable.

And this was the man who would influence how students thought of muggles in the future? Neville wasn't sure that the insights Sherlock could provide to the Auror office would be worth the potential damage to muggle-wizard relations brought on by students exposure to Sherlock Holmes. Worst yet, it was far too late to try and keep him away.

A/N: Okay, wow, this took a long time. I'm sorry to everyone who reads any of my stuff. I am trying to get back on top of it. I actually started to write this one just months ago and most of it got lost because of the Russia being a second world country. I don't know how else to explain it but that.

Also, for the sake of this story, Pomona Sprout is Headmistress after Minerva retired. Also, in the staff room, most professors will be thought of by their first name. Since it's Neville's POV, he will occasionally slip back to last name, especially if it's a professor he learned from.