"Forgive the seeming rudeness, but can you explain to me how you managed to allow another incident to occur in the presence of students?"

Mycroft Holmes disliked traveling from London. Work tended to pile up unconscionably fast and late nights at the office were not on his agenda. But Shacklebolt had put him in charge of the project, which made the alien leaning tensely against the Defense Against the Dark Arts desk his problem. It didn't help that they'd left it two days before informing him.

"You made the mistake of giving me a full-time job," the Doctor said. "I'm in a castle that, frankly, makes Pan's labyrinth look like a garden maze – and I should know, I've been through it twice – and I'm teaching 12 classes of a subject I never studied because I, unlike Professor John Smith, am not a wizard. So you'll forgive me if I seem lazy, but I've been a bit preoccupied."

"Minerva McGonagall informs me that your… inexperience," he said delicately, "with a wand has been remarked upon."

"Well, it's no sonic screwdriver."

He was trying to turn it into a joke, and Mycroft was not amused. "We were assured that your DNA was compatible with our powers," he said, keeping his voice dangerously low.

"Technically, yes, but I've been bouncing around the universe for 900 years and I've never touched a wand. It's a skill, and I haven't been in training since I was 11, unlike you lot."

Mycroft merely stood still, observing. The Doctor frowned, shifting uncomfortably in his robes.

"I'm sorry, Mr. Holmes, but if you want me to continue this charade, it's going to take time."

"You're a time lord. You could search the whole castle and grounds and be back in time to give your next lecture."

"Too risky. The TARDIS is reacting to the magic in the atmosphere. I have no idea if I could be precise enough to make it back within minutes or even hours. I could simply disappear for two weeks, or till final exams in June. Now, while that means a pile of essays I wouldn't have to grade, I don't think it solves our problem."

Mycroft swallowed several more vitriolic replies before saying, "If you're not going to do anything, we -"

"I never said I wasn't doing anything," the Doctor protested, smiling suddenly. "That attack was actually a big help – I've got new information to work with. Type of teeth and claws, that sort of thing. It narrows it down, just knowing it's got teeth and claws – believe me. Just be patient, I'm working on it."

"Yes, as is my little brother," Mycroft said icily. "I won't have him mixed up in this."

"Sherlock is a determined, intelligent young man. I sincerely doubt your permission or disapproval makes a whit of difference to him."

The Doctor's matter-of-fact tone was vaguely insulting. As if this man could understand Sherlock after mere days. Mycroft drew in a slow breath and fixed him with one of his more intimidating glares. "So fix it before he, or anyone else, gets hurt."

The Doctor returned his gaze without flinching. "That's the plan."

The first students in the 3th year Ravenclaw/Hufflepuff section of the class were queuing outside the door as he left. Mycroft checked his watch. The 7th years who were not in Ancient Runes had a free period, and he had one other item of business to take care of before tea with Professor McGonagall.

John Watson was sitting under a tree a ways away from the others. Mycroft recognized the boy from his files, even without the extra research he'd done the previous night. A Muggleborn who didn't know how to keep his head down. Not a suitable companion for Sherlock. He sighed, looking at the sunlit yard with its clusters of students. This was not the ideal location, but he was short on time.

He moved forward, letting his shadow fall on John's parchment. The boy looked up, irritated, expression fading to wary as he took in the strange man before him.

"Mr. Watson."

"Yes?"

Mycroft didn't miss the fact that John had reached for his wand. The St. Mungo's files hadn't been wrong.

"I'd like to have a word with you. Walk with me."

A stubborn vertical line appeared between his eyebrows. "What if I choose not to?"

"That would be unfortunate for you," Mycroft said calmly, propping himself up on his brolly and waiting.

John eyed him another moment and picked up his quill. "So would not finishing this essay."

Mycroft flicked his wand and the paper flew neatly into his hand.

"Oh, very mature," John mocked.

"This won't take long." He waited, but John stayed put. "It's to do with Sherlock Holmes."

On the whole, John Watson reacted much less than Mycroft had anticipated. His eyes widened only for a fraction of a second, but it had been enough for Mycroft to realized he'd hooked his man. John grabbed his cane and stood, making it clear as he did so that he was not amused or intimidated by the man before him.

"How do you know Sherlock?" John asked, lengthening his stride to the point Mycroft knew had to cause him pain. He didn't lag as Mycroft continued at his usual pace into the castle and led him into an empty classroom.

"I've known him for years," Mycroft said finally, laying his umbrella on a desk and turning to face John.

"Friend?" John bit out, leaning against his cane.

"You could say that. The closest thing to a friend he's ever had."

"And that is?"

"An enemy."

That got a definite reaction. John's hand tightened on his wand, eyebrows coming down as his eyes narrowed. It was conceivable that this look had cowed his peers before now. Protective, Mycroft would grant him. Still, these hair-trigger reactions would only make Sherlock worse. Mycroft put on his most dangerous smile.

"Come now, you've known him for three days and you must have seen it. How many friends do you imagine he has?"

"You said this wouldn't take long."

"It won't. Stay away from Sherlock Holmes."

He actually snorted. Mycroft had to admire that. "I'm sorry Mr. – whoever you are, but exactly how is it your business who my homework partner is?"

"I'm a concerned party."

"Concerned how?" John's voice was rising subtly.

The fool wasn't going to budge, that much was certain. Mycroft switched tacks.

"I worry about him. He's am impulsive child and his antics are likely to get him or someone around him killed. I'd like to avoid that if possible."

"Still not seeing where that keeps me from writing research essays with him. If you're so concerned about him, talk to him."

"My involvement would be unwelcome –"

"Shocking."

" – to him, but I do know what's best for him," Mycroft finished smoothly, ignoring the interruption. He cocked his head a few degrees, letting his features smooth into a beneficent smile. "You've had a taste of leadership, Mr. Watson. You understand making unpopular decisions for the greater good, don't you?"

For the first time, the calm contempt slipped, showing the teenage boy's frightened eyes. It was gone in a moment, carefully hidden beneath disinterest.

"Look," John said, spacing his words carefully. "I don't know or care who you are, or what information you think you have about me, or Sherlock, or any other person in this castle. You don't scare me, and I think I'm old enough to pick my own mates."

"Your loyalty is given remarkably fast," Mycroft commented.

"No, I just don't' like you." John's voice was deadpan, the expression on his face blandly polite. "I don't get on with people who try to tell me who is and isn't acceptable company."

Yes. Muggleborn John would be touchy about that. Mycroft adjusted again, begrudgingly impressed with the boy.

"Very well. How about a different arrangement?" He fished in his pocket for a money bag. "I have need of a good set of eyes –"

"Don't." John had raised a hand in clear warning.

Mycroft actually paused, hand halfway out of his pocket, to look at him. John shook his head and extended the hand, palm up.

"I'll have my essay back now."

"I haven't mentioned a sum."

"And you're not going to," John said calmly. "The essay, please."

There was a chance, a faint one, that a personality this immutable could withstand his brother. Whatever else might happen, Mycroft didn't have to worry about this boy being swayed by the talk that always surrounded Sherlock. Rather to his own surprise, he withdrew the parchment and sent it floating into John's outstretched hand.

"Choose your side well, John Watson," he said, brushing past him to the door.

It had been a singularly unproductive trip.