"Have you ever heard of nargles, Professor Doctor?"

A soft, faraway voice drifted to the Doctor's ears, and he paused, mid chew. He had gone to eat his lunch on the Grounds to grade papers and check up on his T.A.R.D.I.S. A plate stocked with bangers and mash as well as a cup of leek and mushroom stew stood to his left, and a sheaf of thick parchment paper lay to his right. And now a strange looking girl stood in front of him, not quite meeting his gaze but rather staring dreamily off at a patch of sky just to the right of his head.

Her school robes marked her as a second year Ravenclaw, and what looked like a pair of radishes dangled from her ears. How… interesting.

"I'm sorry, but I don't think we've met." The Doctor stood, wiping his hands on his suit pants.

The odd blonde stared at his proffered hand for a few uncomfortable seconds, before taking his wrist and shaking that instead. Her dad had written in the Quibbler that microscopic nymphs called the Coopoo hid under people's fingernails, and she couldn't be too careful. If the Doctor was surprised by this strange greeting, he hid it well.

"I'm Luna…" she said slowly in the faraway quality of hers. "Luna Lovegood." Inclining her head at the unfinished meal at the Doctor's feet, she asked offhandedly. "Am I interrupting your meal?"

"Ah," the Doctor glanced at the cold stew and dirty plate as if he had forgotten about it entirely. "I wasn't that hungry anyways."

Luna nodded a few times, and then proceeded to stomp down on the lukewarm sausages and mashed potatoes with her feet. She wiped her shoes clean on the grass as if the whole thing was completely normal.

"The Triple Eyed Prehe is attracted to elf-made meals that are left unattended," she said with a dreamy smile. "Did you know that?"

"Erm," The Doctor glanced at the strange student to the decimated remains of his lunch, and back again. "No, I can't really say that I did. Thanks, though. You know, for catching that. Could've been…bad."

"It wasn't a problem." Luna said cheerfully. She began to look off once more into the distance, and this time the Doctor turned to see what she was looking at.

"Oh, no," he exhaled slowly, his eyes wide with shock.

"Is your blue box supposed to be doing that?" Luna asked amicably. The T.A.R.D.I.S. was no longer by the Quidditch pitch like it had been when the Doctor started eating, but rather kept aloft high above the lake by a group of wizards from the Ministry. Their wands were trained on the police box, and as the Doctor and Luna watched, the Ministry wizards set the T.A.R.D.I.S. back down on the grounds with a delicate thump. From what the Doctor could tell at a distance, it looked like they were running a series of tests.

Not good, very not good.

"Oy!," he shouted, waving his arms as he ran towards his precious T.A.R.D.I.S. and its captors. Luna stared after the strange man for a few seconds, watching his long brown robe billow out behind him, before turning and walking away, tugging the latest edition of the Quibbler out of her robes.

"Excuse me," the Doctor said in an out of breath burst. "Just what do you think you're doing with my box?"

One of the wizards who had been merely supervising turned to him, looking bemused by the Doctor's impudence. He was of the short, squat sort with a mustache several sizes too big and intricate robes that would better fit Hagrid.

"Jus' a routine inspection, good sor," he answered with a tip of his hat. The short wizard's robes were flowingly embroidered with the name Morionem Quinn. "Magical items of this size must be registered with the Ministry."

"Registered?" The Doctor exclaimed, and his right eyebrow seemed to take on a life of its own, twitching slightly. "And what does 'registering' involve, exactly?"

Morionem shrugged. He was only the supervisor and didn't fully understand the process himself, so he didn't see why this tall man needed to know either. Keen to pass the Doctor's irksome and inquisitive questions on to someone else, he jerked his thumb over his shoulder. "Why don't you ask 'em?"

"I will, thank you." Jamming his hands into his coat pockets with purpose, the Doctor gave Morionem a salutary glance and moved on to the witches and wizards huddled around his precious T.A.R.D.I.S. They seemed thoroughly baffled by the locking mechanism on the doors alone, not to mention the humble and weathered sign reading "Police Telephone, FREE for use of PUBLIC."

"It says here 'pull to open.'"

"I can see that, Ewan. Do you think we haven't tried that ten times already?"

"Stupid misleading sign. 'Free for use of public,' my arse."

"Reckon there's some sort of Dark Magic keeping it shut?"

"Don't be daft, it belongs to a teacher. Dumbledore wouldn't let anyone working for him have anything to do with the Dark Arts."

"There is that Snape bloke…"

The Doctor rocked back on his heels impatiently just a few feet from the T.A.R.D.I.S.

"If I may have a word," he ventured to interrupt. Four aggravated faces turned to look at him. "That is my…box you're assaulting."

"Your box?" One reedy witch piped up curiously, but a taller wizard elbowed her out of the way. It was clear he was the one in charge. He looked to be a good man, albeit very frustrated at the moment.

"Yeah, it's an…" the Doctor grasped at straws. "an office decoration. Yeah, it's an office decoration! It's not supposed to open, because, you know, then it wouldn't be…decorative."

"Mighty strange office decoration, that is, Rhysand."

"Shut up and let the man talk, Ewan."

The Doctor nodded profusely, and pulled the psychic paper from his robes. "Besides, I've got it registered, see here? All this thing does is make noise and light up, but it's 'registered' anyways." At the assembled wizards' expressions, he put in helpfully. "For safekeeping."

Rhysand snatched the psychic paper from his hand, methodically going over the paper with his wand. His brow furrowed. "We got a tip from a student here about an unregistered transportation device on the school grounds. Malfoy, I think it was. dad is the big cheese, but I should've known it'd be wrong. These papers seem legitimate enough to me."

"Told you this would be a waste of time," the reedy witch murmured reproachfully.

"Shut it, Ewan," Rhysand reprimanded. Turning to the doctor, he gave a little apologetic bow. "Sorry to waste your time. We can put your, erm, office decoration, back where it was."

"Thank you!" The Doctor said with a grin swollen by relief. He patted Rysand on the back to the older man's surprise, and walked away.

He had decided, despite the initial turbulence, that Hogwarts was quite a nice place. Quite a nice place indeed.

_()_

The Defense Against the Dark Arts classes taught by the Doctor passed by faster than anyone had really expected, and his short-lived tenure would be missed more than anyone could have predicted. After all, he was only there for a few short days. But in that brief time period, he taught of fantastical dark creatures unheard of by the wizarding world, and his lessons would go down in the very depths of favorite Hogwarts legend.

The day before the Doctor left, the fourth years were a buzz about the Vashta Nerada, and the first years were having trouble going to sleep at night, haunted by visions of the Cybermen. And no third year ever quite forgot the unique experience of their encounter with a Weeping Angel.

"So then, you're on the mend?" the Doctor asked Lupin one morning at breakfast. The shabby professor nodded tiredly, looking more haggard than usual, but he clasped his utensils firmly and had quite the hearty appetite. The other teachers in the Great Hall couldn't seem to pass him the serving platters fast enough, until McGonagall ordered extra food from the house elves in a somewhat snappish tone.

"I'm feeling much better, thanks," Lupin replied after swallowing down a rather large piece of sausage. He struggled a bit, feeling the piece of food get lodged in his throat, but the Doctor reached out and gave him a helpful slap on the back.

"Easy there," the Doctor chuckled, and Lupin grinned easily back. After a few minutes of comfortable silence – which was mostly occupied by the sound of happy eating – the Doctor said. "You know, you're lucky to have the job you do. I think I'll miss it here."

"Hmph," Attacking his third piece of toast, Lupin raised an eyebrow. "I don't know if my students will be excited to have me back. You were quite…engaging, as I understand it."

"Weeellll," the Doctor stretched the word out with an easy smile. "I may have been a bit unorthodox."

"A bit," the shabby professor agreed. He wasn't deaf, he had heard the stories. "Maybe my students will be relieved to have me back, then. I thought I'd teach this morning's second year class, if it's all the same to you."

Lupin didn't miss the flash of disappointment that crossed the Doctor's face, but if he hadn't seen it he would've thought the strange man was relieved.

Stuffing his mouth full of banana, the Doctor asked offhandedly. "Hey, do you know why your usual sub couldn't stand in for you this time?"

"Snape?"

"Mmm." The Doctor nodded vigorously.

"He had other things on his mind, I suppose. There was the Potions conference in Dublin that lasted a few days. No one's really seen him this past week, and he's got the Bloody Baron standing in for him as the Potions Master."

"Interesting. 'Suppose I might see him before I head off, but chances are against it."

Shocked, Lupin paused his eating. "You're leaving already? I thought you said you liked it here."

"I do," the Doctor said, and for a few seconds he looked older, more stretched. "I like everywhere I go, but I don't stay. I never stay."

Lupin frowned, feeling that he may have misjudged this man.

"You're welcome to help out with the lesson this morning, if you'd like." He offered tentatively.

But the Doctor merely declined with a polite smile and excused himself from the table.

Lupin watched as the strange man walked away, and the professor couldn't remember a time he had seen someone look more lonely than the Doctor looked in that moment. The Doctor, the man who traveled to so many places, and yet never stayed.