A/N Sorry the chapter's a bit late, our school musical had its last productions this weekend which meant my free time was 0. Bonus points to everyone who caught that the HGttG reference was the star name Babel Fis 42 on Harry's test. :)

To clear up any confusion, this story spans from the beginning of Half Blood Prince all the way through to the end of Deathly Hallows. So, really, the story's not even half way done yet. That can be a good thing or a bad thing, depending on how much you like the story. :)

CHAPTER THIRTEEN

The first thing that the Doctor was aware of when he came to was the fierce pounding inside his skull. The second thing he noticed was that whoever had been inside his head was definitely gone, and his mental barriers were still intact.

The Doctor's eyelids felt so heavy that it was quite a struggle for him to finally pull them open. Wincing slightly at the light that flooded in, he managed to get his eyes to cooperate long enough for him to determine where he was. He seemed to be lying on his side on the cold stone floor of his classroom. So he hadn't been captured or something while he had been out…

Groaning slightly as the aching pain in his head seemed to peak, the Doctor could barely find the strength to drag himself up into a sitting position. His whole body seemed to have tripled in weight.

Strange…he hadn't regenerated, had he? Slightly panicked, the Doctor raised his hands to feel himself. Same bad skin, same crest of brown hair, same skinny body. The Doctor relaxed and let his hands fall back onto his legs. The…thing inside his head hadn't forced him into regeneration. Good – he didn't have many left, and he didn't want to waste them.

The reality of his situation finally came crashing down on the Doctor. He admitted it to himself – he was a bit frightened that some being somewhere in the universe had the ability to enter his head at will and, apparently, activate his neural pain sensors and…for lack of better words…turn him 'off' for a short period of time.

Exhaling sharply, the Doctor managed to haul himself to his feet using the corner of his desk for support. Shakily releasing the edge of the desk, his knees buckled and he would have fallen over if he had not grabbed the table again instinctively. As he grasped the wood for support, the Doctor noticed a paper tied with a lilac ribbon that he had knocked off the table. Crouching over and still holding the desk with one hand to steady him, the Doctor picked up the piece of paper and untied the ribbon. If he had had the energy, the Doctor would have reached for his glasses in his coat pocket. Instead, he just squinted to make out the flowery print.

Dear Friend! You Have Been Cordially Invited To:

Horace Slughorn's Christmas Celebration!

When: The Last Day of Classes at 7:00!

Where: Professor Slughorn's Office!

Who: Yourself and ONE (!) Friend!

WEAR YOUR NICEST DRESS ROBES!

The Doctor stared at the invitation a lot longer than he normally would have. When had he been invited…? Oh, he remembered, it was a week or so ago, when he had gone to Hogsmeade.

The Doctor considered not going to the "Christmas Celebration". After all, from what Slughorn had told him, there were going to be quite a lot of Slughorn's students at the party, and the odds were not in his favor for him not meeting up with one of his own students there. He could tell that he had probably scared them all during his…episode during class, and he wasn't quite sure how he was going to explain everything to them without telling the truth.

On the other hand, not going might be even worse for his reputation. He had a feeling that Slughorn was going to be looking for him at the party, and if he didn't show up, Slughorn was going to ask awkward questions that he didn't know how to answer. It might also give the impression that there was something seriously wrong with him to the students, and then they would tell the other teachers, and then there would be more questions…

As if people weren't suspicious of him already…

After deliberating between the pros and cons of going to the party, the Doctor finally reached a conclusion. He would go. He didn't want to seem suspicious, and, to be honest, a party might be a nice break from everything going on at the moment.

Really, it was just a party. What could possibly go wrong?

The Doctor adjusted the bowtie on his suit. He had no idea what "dress robes" were, but he really hoped they were the "Muggle" equivalent of a nice suit.

The Doctor remembered the last time he had worn this suit; he had gone to see the "de-aging miracle machine" with Martha. That was the first time he had met her family…though he had seen plenty of them later that year…

Closing his eyes and willing the memories of the Year that Never Was to recede, the Doctor took a second to compose himself. He was going to a party, he was going to have a good time, and he wasn't going to dredge up any ghosts of the past.

Taking a deep breath, the Doctor pushed open one of the wide doors of Slughorn's "office".

There was no doubt about it; Slughorn's office was much bigger and fancier than it appeared to be on the outside.

It's bigger on the inside, the Doctor thought to himself with a small smile.

The office was decorated with giant floating red lanterns that glowed warmly with candle light. Tinsel was strewn about, and a roaring fire kept the room nice and toasty. There were students dressed as waiters milling about with trays burdened with appetizers and drinks. The rest of the guests were clustered together in small groups, all engaged in conversation. A band was playing in the corner, where some students and a few adults were dancing together. The Doctor even saw a photographer mingling with the guests, occasionally snapping a photo or two.

The booming voice behind him took the Doctor by surprise. "Doctor! You made it!"

The Doctor turned around to see the rotund figure of Horace Slughorn and another tall, reedy man approaching him. The Doctor did his best to smile as Slughorn crushed his fingers in a surprisingly strong handshake. "Hello, Horace."

"Good to see you, good to see you…ah! I haven't introduced my good friend, Dilbert Watson. Dilbert here is the Head of the Muggle Relations Department at the Ministry of Magic."

"How do you do, I'm the Doctor," the Doctor said, reaching out to shake Dilbert Watson's hand. Dilbert shook his hand firmly.

"The Doctor, eh?" Dilbert said. "Interesting name."

"Yes, well, my parents never did like to fit in with the crowd," the Doctor said with a smile. This was not, strictly speaking, true, but the truth would have taken a lot of explaining that he really didn't want to do.

"Dilbert, I think you'd like to know, but the Doctor here is actually a muggle," Slughorn said. Dilbert raised his eyebrows in an interested way.

"Really? Why doesn't the Ministry know about this?"

"Oh, er, I'm kind of…new," the Doctor said quickly. Best to stay away from questions.

"New?"

"I've been the Astronomy teacher ever since the old professor…erm…left."

"I see…and, forgive me for asking, but…do you have any idea how you can actually see the castle? I thought that Hogwarts was protected by an Anti-Muggle Perception charm…"

"Oh…" The Doctor thought quickly. What would a regular human say? "Maybe I have a highly developed sensory perception that enables me to disregard all extraneous filters so I can see…things…for what they…are…" Aaahh, too complicated…

"I see…" Dilbert said again, though from the look on his face, he didn't 'see' at all. Thankfully, he didn't seem to want to pursue the matter any further.

"Oh, the Doctor here is a bright young chap," Slughorn said with a grin. "I can't understand a word he says, but that's muggle talk for you…no offense, Doctor…" Slughorn took a deep drink out of the glass he was holding and hiccupped.

"So…going home for the holidays, then, Doctor?" Dilbert asked, seemingly keen on changing the subject. "Going to visit some family?"

"Nah, I don't have any family, just me," the Doctor said, shrugging his shoulders in a nonchalant fashion.

"Ah, what a shame. You could still visit friends…"

"I'm staying here for Christmas. And yourself?"

"My wife and I are spending it together, and our son might pop by on Christmas Day…"

"Dilbert! Look! It's Madame Lucille and Lady Beatrice! We simply must say hello to them…good seeing you, Doctor…" Slughorn said as he grabbed Dilbert's arm and yanked him away.

"…Goodbye?" the Doctor said, a bit surprised by the abrupt departure. He shrugged and walked away from a group of seventh-year students that had been drifting closer while he had been talking to Dilbert and Horace.

A waiter passed by, holding a tray of tall glasses filled with mead.

"Don't mind if I do," the Doctor murmured as he swiped a glass off the tray just as the waiter whizzed by.

A series of poorly concealed whispers behind him made the Doctor turn around. A group of his Gryffindor sixth years were talking in not very quiet tones behind their hands. As soon as he turned around, they all became silent, leaving no doubt in the Doctor's mind that they were talking about him. Raising his eyebrows and giving the girls a pointed stare, he again moved away. As soon as they thought he was out of earshot, the whispers started up again. No matter, there were more important things in the universe…or, apparently, the multi-verse…to worry about.

The Doctor's mind was so disconnected from his actually physical movements that he ran straight into a mane of wild, frizzy blond hair.

"Oh, excuse me…" he started to say, when the woman he had run into spun around. She was wearing a number of colorful shawls draped dramatically around her shoulders, and had on a necklace that seemed to be made of mirrors, giving her the likeliness of an exotic beetle.

"Doctor!" the woman said with a hiccup. A whiff of what smelled suspiciously like cooking sherry hit the Doctor in the face.

"Erm…sorry, remind me of your name…?"

"Ah, yes, I sometimes forget that not everyone posses the Sight that I do…Trelawney, my dear, Sybil Trelawney, Professor of the fine art of Divination…"

"Oh…all righty then…nice to see you, I should just be going-"

"Hello," said a wispy, dreamy voice from behind Professor Trelawney. Peering from around Trelawney's massive hair, the Doctor cringed when he saw that it was Luna Lovegood, Hermione Granger, and Harry Potter. Luna and Hermione, he didn't mind, but he would really rather avoid Harry…because Harry had had questions about him right from the start…

"Good evening, my dear," Professor Trelawney said. She squinted at Luna, as though she was having trouble bringing her into focus. From the way Harry wrinkled his nose, the Doctor could tell that he had smelled the sherry as well.

Luna and Trelawney were engaged in a conversation about Trelawney's Divination classes, and Hermione and Harry were quickly whispering together about some topic or another. None of them seemed to have noticed Doctor, so he started to edge away quickly…maybe he could get away without being missed…

"Doctor!" Trelawney half shouted, throwing an arm out and dragging him back. "Have you met my…hic!...friend Luna?"

The Doctor gave a forced smile as he was pulled right into the middle of all the conversation. "Yes, we've met," he said.

Hermione had disappeared. Harry blinked as the Doctor was pulled into view.

"Evening, Harry," the Doctor muttered.

"Evening, Professor," Harry said. "Er…sir, I was wondering, during class this afternoon…"

"It was a migraine," the Doctor lied quickly. "I've been…having them for a while."

"That's not what I-" Harry started to say, but Professor Trelawney cut him off.

"Harry Potter!" she said, in a deep, slightly drunken voice.

"Oh, hello," Harry said unenthusiastically.

"My dear boy!" she said in a very carrying whisper. "The rumors! The stories! 'The Chosen One'! Of course, I have known for a very long time….The omens were never good, Harry…for you and the Doctor here…such darkness I have seen in his past and your future…"

Harry blinked. "Excuse me?"

"Heh heh…what on earth do you mean, Sybil?" the Doctor laughed weakly, trying to divert Harry's attention.

Trelawney continued on as if she had not heard either of them. "But why have you not returned to Divination, Harry? For you, of all people, the subject is of utmost importance!"

"Ah, Sybil, we all think our subject's most important!" said a loud voice, and Slughorn appeared at Trelawney's other side, clutching a glass of mead and an enormous mince pie. The Doctor could not think of anyone he would rather see less at the moment, but Slughorn didn't seem to sense the awkwardness of the situation.

"But I don't think I've ever known such a natural at Potions as Mister Potter here!" Slughorn said. "Why even Severus-"

To the Doctor's horror, Slughorn threw out an arm and seemed to scoop Snape out of thing air toward them.

"Stop skulking and come and join us, Severus!"

The Doctor revised his previous statement. Slughorn had found someone he would rather see less: Snape. Both Harry and the Doctor grimaced and stared awkwardly at the floor as Snape joined them.

The conversation continued for a while, while the Doctor remained staring steadfastly at the floor, determined not to look up for fear of being forced to join in the talking.

There was suddenly a scuffling sound that made the Doctor finally look up. Argus Filch was dragging Draco Malfoy into the room by his ear.

"Professor Slughorn," wheezed Filch, "I discovered this boy lurking in an upstairs corridor. He claims to have been invited to your party and was delayed in setting out. Did you issue him with an invitation?"

Malfoy pulled free of Filch's grip, looking furious.

"All right, I wasn't invited!" he said angrily. "I was trying to gatecrash, happy?"

"No, I'm not!" said Filch, a statement at complete odds with the glee on his face. "You're in trouble, you are! Didn't the headmaster say that nighttime prowling's out, unless you've got permission, didn't he, eh?"

"That's all right, Argus, that's all right," said Slughorn, waving a hand. "It's Christmas, and it's not a crime to want to come to a party. Just this once, we'll forget any punishment; you may stay, Draco."

The Doctor wasn't particularly interested in this turn of events; the more fascinating sideshow involved the people standing around him. Only Filch's face was predictable; outraged disappointment. Draco, however, looked equally unhappy by Slughorn's verdict. Snape was looking at Malfoy as though both angry and apprehensive. Harry had a look of deep concentration…he had obviously noticed the side show as well.

As the Doctor watched silently, Harry continued to scrutinize Draco's face. He seemed to be just as puzzled by Draco's odd reaction as the Doctor was…

"I'd like a word, Draco," said Snape suddenly.

Oh ho, the Doctor thought. Now this is interesting…

"Oh, now, Severus, it's Christmas, don't be too hard – "

"I'm his Head of House, and I shall decide how hard, or otherwise, to be. Follow me, Draco." With a swish of his long black cloak, Snape and Malfoy disappeared out of Slughorn's office.

The Doctor took a quick glance at Harry. Shuffling feet, shifting glance between Luna and the door, excessive blinking…he was going to follow Snape.

"I'll be back in a bit, Luna – er – bathroom."

So you're going to do a little recon, eh, Harry? The Doctor thought, while fingering the perception filter hidden underneath his coat jacket. Well, two can play that game…

Moving away from Trelawney and Luna, the Doctor activated the perception filter, and with a quiet whirr, it clicked on and he turned 'invisible'. Then, careful not to tread on anyone's feet lest he give away his position, the Doctor snuck out the door after Harry, Malfoy, and Snape.

Harry did his best to breath quietly as he moved out into the deserted hallway, in case Malfoy and Snape were nearby and could hear him. He pulled the Invisibility Cloak out of his pocket and was about to pull it on.

The voice behind him made him jump about half a meter into the air.

"Going somewhere, Harry?"

Spinning around, the cloak still clutched in one had, Harry almost had a heart attack when he saw the Doctor standing right behind him.

"…Doctor?" Harry spluttered. "But…how…?"

"So what's this, then?" the Doctor said, running one of his hands through the cloak's silvery fabric. "A molecular scrambler integrated into the cloth? Oh, that's clever, wish I'd thought of that…"

"Sir?" Harry asked, confused as usual when it came to the Doctor.

"Never mind, never mind, just put it on," the Doctor said, throwing the cloak over Harry and watching as he vanished.

"Veeeeery good," the Doctor said slowly. "Oh, that is beautiful. I can't see you at all!"

Harry stood there awkwardly for another moment. "Uh…"

"What are you still doing here? You're going to lose them!" the Doctor said indignantly.

"I…what?"

"Snape and Malfoy, of course."

"And…you aren't going to stop me following them, sir?"

"Of course not! You should have seen me at the academy…never mind that, get going! They went that way." The Doctor pointed off down a corridor to the left.

Harry turned to look, and when he turned back around, he was again surprised to see that the Doctor had vanished.

Raising an eyebrow under the cloak, Harry nevertheless set off down the hallway.

Malfoy and Snape were conversing in hushed tones inside a deserted classroom. Harry listened as closely as he could. Mistakes…an Unbreakable vow…and…what was that?

A crackle of energy, rather like static on a television, appeared in the corner. Harry was shocked to see the dim form of the Doctor hunched over a few feet away, listening through the wall.

"Blasted thing…" he heard the Doctor mutter. The Doctor hit his waist, and he suddenly disappeared again.

Almost too distracted to keep listening, Harry barely caught the end of Snape and Malfoy's conversation, which was more than enough to make him extremely confused and set his mind racing.

What is going on? Harry thought desperately, not for the first time that year.

A/N There was a Hunger Games reference Try to find it! More bonus points XD