Thanks to surprisedbylife, streamersinthefirmament, and pensandpearls on Tumblr for looking this over for me.

This takes place during the chapter "The Parting of the Ways" in Harry Potter and the Goblet of Fire. Other than the fact that Barty looks like the Doctor, it's entirely book-verse. Takes place sometime after "Last of the Time Lords" for Ten.

As soon as it saw him, the Dementor which had accompanied Minister of Magic Cornelius Fudge into the Hogwarts Castle swooped down upon Barty Crouch Jr. and gave him its dreaded Kiss. Once the Dementor had done this, Cornelius Fudge did not enter the Defense teacher's office, instead choosing to escort the Dementor off the Hogwarts grounds before going to speak with Professor Dumbledore. So it was only Professor Minerva McGonagall, Professor Severus Snape, and Winky the house-elf who bore witness to the rather startling aftermath of said Kiss.

The shocking event itself came in the form of the supposedly-soulless Death Eater, who, after the Dementor had left the room, proceeded to sit up, attempt and fail to clutch his head (as he was still bound with the ropes Professor Dumbledore had conjured), and cry out in pain. It was not often that either Professor McGonagall or Professor Snape were shaken to the point of speechlessness, but this was, understandably, one of those times. Winky, however, was surprised enough to stop crying, and speak tentatively. "Master Barty?"

Barty Crouch Jr. did not appear to understand the question. In fact, his whispered response would have immediately been put as the definition of "non-sequitur" had anyone who worked on a dictionary been present. This puzzling answer consisted only of two words: fob-watch.

By this point, Professor McGonagall had recovered enough of her wits to ask the natural question which would follow such a perplexing reply. "What are you talking about, Mr. Crouch?"

He was able to give her a longer answer than before, although not one that was less confusing. "I need…there's a fob-watch…somewhere in here…ooh, my head…summon it, please, I'll explain later, in a minute, I…ow…really need it."

Had most of the vast majority of her former students asked her to summon something while obviously in pain, Professor McGonagall would not have hesitated to do so. However, since this particular former student of hers had just caused great pain to one of her current students and assisted in the rebirth of one of the evilest wizards in history, she should not be blamed for not doing as he asked. Instead, she pointed her wand at him (Professor Snape had raised his wand the second Barty Crouch Jr. had done something besides slump soullessly against the wall, of course), and told him in no uncertain tones to explain what on earth he was talking about.

"I won't have time to if I don't get that watch on account of my head exploding," he snapped sharply. The argument might have continued until his companions learned whether or not Barty Crouch Jr.'s head would indeed have exploded if he had not soon possessed the fob-watch in question. However, as Winky summoned the watch with her own magic at that moment, the question was made moot. Before either professor could react, he had opened the watch, and they stared in awe as a golden light came forth from it and enveloped his head.

He was still for a second, then muttered, "head, shoulders, hearts, knees, and toes, I'm fine." Springing to his feet, the pain in his head apparently forgotten, he somehow managed not to fall over and also to place his hands in the pockets of his robes. He then proceeded to smile at his baffled companions, and say, "Hello. Right, sorry, you must be very confused. I'm the Doctor. Don't suppose you'd mind untying these ropes?" Neither Professor moved. Winky might have done as he asked, but she was too shocked to move. He sighed, and then continued to speak. "Basically, I'm an alien, and my consciousness got put into that watch by a very advanced alien device, which also turned my body temporarily into that of a human. The Dementor very kindly made me remember who I was when it sucked Crouch's soul out of my body, but as my brain can't stay in a human body, or my head will go BOOM" – here he attempted to mime the aforementioned explosion, but only manage to move his bound hands a little underneath the ropes – "I needed to open the watch to make my body the right species again."

Given that Professor McGonagall and Professor Snape had both informed Muggleborn wizards and witches about the magical world, they should perhaps have been more open to the idea that there could be more forms of life in the universe than those of which they knew. However, both professors continued to stare at him – Professor McGonagall unable to hide her shock and Professor Snape's eyes as blank as always – and neither lowered their wands. After a very short pause, Professor Snape said snidely, "Really, Crouch, if you're going to lie to us, at least try and make it believable. How is it that you still have a soul?"

He smiled at them, apparently unconcerned by the wands pointing straight at his chest. "Touch my chest."

"Excuse me?" Both Professors spoke at the exact same instant.

"Just touch it for a minute – I promise I won't bite." Given that the strict professors were very obviously annoyed, humor and smiling was perhaps not the wisest course of action that Crouch Jr. – or the Doctor, as he must now be called – could have taken. However, no one had ever accused the Doctor of having any common sense. Indeed, he would have been very offended at the thought that someone might believe he had any.

Professor Snape glared at him in a way that made it very clear that he trusted him about as far as a bowtruckle could throw a basilisk. (Those readers who did not pay attention in Care of Magical Creatures should be informed that that bowtruckles are less than eight inches tall – in other words, Professor Snape did not trust the Doctor at all.) However, Professor McGonagall stepped forward and placed the hand not holding her wand on his chest. A moment later, she stepped back in shock.

"What are you?" she asked in a steely voice that would have been commended for its steadiness, had an impartial observer been in the room. Now Professor Snape stepped forward, and he too touched the Doctor's chest. It was a credit to Professor Snape's talent for hiding his emotions that even the Doctor was barely able to see a hint of his confusion in his expression as he stepped back. Winky looked worried at Professor's McGonagall's obvious befuddlement.

"Master Barty, is you being alright?"

"Don't worry Winky, I'm fine. Better than I've been in a while, actually. Professors, I told you, I'm an alien; that's why I've got two hearts. You know that no species on Earth – magical or Muggle – has two hearts." The Doctor stopped speaking, and then decided to explain further. This action was motivated by Professor McGonagall's raised eyebrow. The Doctor was impressed by her ability to inform him merely by raising an eyebrow that if he did not explain himself, he would find himself on the receiving end of a nasty jinx or perhaps thrown to a Blast-Ended Skrewt. He sighed, "I'm a Time Lord. We're a race of incredibly technologically-advanced time-travelling aliens. I didn't mean to interfere in your planet's history," – he coughed, a sound which his companions could have sworn sounded like "this time" – "I just wanted to be an ordinary human for a couple months, but unfortunately another alien overrode the safeguards on the device I was using and I didn't notice until it was too late."

"If Master is being a powerful alien, how is anyone being able to hurt Master?" Winky looked as if she was having trouble understand what the Doctor was saying, although, to be fair to her, the same could be said of a large percentage of people who had spoken to the Doctor. It could certainly be said of Professor McGonagall who was even more shocked at finding out that there was life on other planets than the Wizards' Council was when Uric the Oddball tried to convince them that Fwooper song was beneficial to the health while wearing only a dead badger on his head.

The Doctor smiled again, although this one was most certainly not a happy grin. Professor Snape, who prided himself on being able to read people was unable to decide whether this smile was sad, kind, or a mixture of both. "The trouble is the other side can do magic too. Well, understand extremely complicated space-time machinery, as the case may be, but that doesn't quite have the same ring to it, don't you think?"

Ignoring the Doctor's question, Professor Snape asked the Doctor a question of his own.

"Is the alien who did this to you dangerous and are they coming here once they find out you're no longer human?" Despite themselves, the two professors were starting to believe he was indeed an alien; there was something in his face – they couldn't say what exactly it was – that seemed very alien.

"He's dead," replied the Doctor shortly and it was clear from his tone that the subject was closed.

Or not, as Professor McGonagall chose to continue Professor Snape's line of questioning, rather than tactfully change the subject. It was not often that Professor McGonagall was deliberately obtuse, but this was, after all, not a normal day, and Professor McGonagall's nerves had already been stretched to the breaking point. She pierced him with the same impressive glare which was famous (or possibly infamous) among her students.

"If he's dead, how did he interfere with the device which turned you human?"

"He did it several years ago, I just didn't notice, as this isn't exactly a device I use every day," the Doctor said tightly. "It's not like I wake up, have a cup of tea, pop off the shops, turn myself into a human, go home, have dinner, go to bed. I've only used it once before. I needed to use it now, just for a few months, because there was this other alien that wanted me to use my rather large knowledge of temporal engineering to help his evil plan – if it had been a good plan, I wouldn't have minded, you know, turning a weapons factory in a banana grove or getting unlimited rice pudding or …." The Professors were glaring at him again. "Er…anyway, his plan was time-sensitive, so since when I'm human I don't have all my Time Lord knowledge, I figured I'd save myself the inevitable bruises that I'd get when I refused to help him. Villains are always so predictable, if I had a knut for every time I've heard 'you were made to be ruled' or 'you will obey me' or 'I'm invincible,' they're all loonies, really…." The Doctor stopped talking, as both Professor McGonagall and Professor Snape's glares had intensified. It seemed neither professor cared for the admittedly rather long tangents that often came up whenever the Doctor spoke.

Professor Snape had a (correct) hunch that the Doctor was not, in fact, telling them the whole truth, while Professor McGonagall was in the rare position of having absolutely no idea how to respond to what she had just been told. So decided to do what she always did in such extraordinary situations. Then she remembered that this would probably be somewhat unwise, as the man she would have contacted was currently escorting Harry Potter into his office to find out what had happened when He-Who-Must-Not-Be-Named returned earlier that evening.

It was very unfortunate that Professor Dumbledore was not there, as he would not have been at all shocked upon learning about the existence of aliens. This was mostly because when he was only ten years old, a blue box had appeared out of thin air right in front of him. A man with a long scarf and curly hair and a young blond woman had stepped out of it. The man had remarked disappointedly that they were not in Paris and then proceeded to sort out the problem the village was having with some Raxacoricofallapatorians, as Albus learned the large green aliens were properly called. He had been very pleased to be allowed to tag along with the strangers from the box and, at the end of the adventure, had received a wider knowledge of the world and a bag of jelly babies for his trouble.

Returning to the scene in the Defense teacher's office, Professor McGonagall and Professor Snape looked at each other, and then, without speaking, stepped back to converse with each other in private. They were well aware that Cornelius Fudge would be returning to the castle very soon. As neither of them wanted the Minister to find out that Barty Crouch Jr. was apparently really an alien called "The Doctor," they knew they should probably go find him. But it was of course ludicrous to suggest that either professor would consider leaving someone so untrustworthy alone. Although these two facts were known to both professors, the first bit of their conversation was spent in whispering them worriedly. Neither professor wanted to leave him in any room alone, but Professor Snape thought it would be the act of an idiot Gryffindor to leave him with another Professor. After Professor McGonagall suggested that Professor Flitwick would be a decent choice, Professor Snape reluctantly agreed. However, he did add that it might be prudent to stun their companion.

"No need to stun me, I'll come quietly." The two turned to face the other occupants of the room. To their surprise, Barty Crouch Jr. was not where they had left him. Instead, he was sitting cross-legged on the desk, propping his head up on one arm. Winky had clearly released him from the ropes and he was listening to their conversation with great interest. He hopped up off of the desk and stepped towards them.

"When Professor Dumbledore asks why you're not guarding me, lie to him, will you?" Professor McGonagall opened her mouth to argue, but The Doctor cut her off. "I know you'll tell him the truth later, but your Ministry's not supposed to know about aliens yet. Course old Fudgy Fudgity Fudge Fudge probably wouldn't believe you if you told him the truth, but no sense in taking the chance, hmm? I don't want him speaking to the Muggle Prime Minister and connecting any dots, although quite frankly I don't think he's smart enough to do…." He trailed off, as Professor McGonagall had raised her eyebrow again. This event did not contain the promise of pain, however, just the wisdom of insulting their Prime Minister so openly (although privately she agreed with him about Fudge's intelligence). "Oh, that was rude, wasn't it!? Sorry, I can be a bit rude, rude and not ginger." He looked morose for a second.

"How do you know when wizards are supposed to find out about aliens? And what do you mean the Muggles know about aliens?" Professor Snape's tone was incredulous, and hinted at the fact that he did not believe that Muggles could know anything that wizards did not.

The Doctor raised an eyebrow.

"I'm a time traveler, haven't you been paying attention? Although, I suppose most of my people might not've known the exact year, just, I don't know, the decade maybe, 'cause they didn't really care about the particulars of a random Class Five planet." Forestalling the next question, he continued, "but I've always rather liked Earth. You humans are just brilliant." He beamed at them, like a proud parent smiling at a child who had just done their first bit of accidental magic. "And as to your first question, most Muggles don't know about aliens, just a few. They're the reason you lot haven't been conquered yet. Although, how you all can remain completely in the dark after the last decade… or maybe it was the '70s, not the '80s… anyway, it's really astounding. I don't know what's more impressive, your ability to survive or your ability to overlook really obvious things."

"What do you mean about the last few years," Professor McGonagall asked sharply. Professor Snape had questions of his own, about the Doctor's people and why he had spoken of them in the past tense, but as he was interested in the answer to Professor McGonagall's question, he remained quiet.

"Well, tons of aliens have tried to invade… there were the Autons, they're these living plastic things, they tried to invade a couple of times… the Sontarans have too, they're a clone race, look kind of like potatoes, and I've lost count of how many times the Daleks have tried to invade."

"Good gracious!"

"Yes, I don't think I'll ever get done saving you lot." He smiled fondly.

"Why?" Professor McGonagall fixed him with a sharp glance.

"Why what?"

"If you're such a powerful alien, why do care about humans?"

Surprisingly, it was Professor Snape who answered the next question. "Because he couldn't save the Time Lords, of course."

The Doctor froze. "How do you know about that?"

Snape smirked. "I didn't. Your babbling told me everything I needed to know."

"Actually, I've been saving you lot long before they died," the Doctor said, his voice extremely frosty.

Fortunately, Professor McGonagall then stepped in, as the eventual outcome of the Doctor and Professor Snape's conversation, should it continue in such a manner, would have been very bad indeed. Unfortunately, Professor Snape then decided to do something that was rather stupid. Indeed, very few people (not counting attractive French aristocrats), would have been so idiotic as to attempt to read the Doctor's mind when he was in one of his "I am the Last of the Time Lords, Woe is Me" moods. However, as Professor Snape was unacquainted with the Doctor and his moods, he can perhaps be forgiven this serious lapse in judgment.

"Don't. You. Dare." The Doctor didn't move or raise his voice; however, his absolute fury was clear to everyone in the room.

"What?" Professor McGonagall and Winky spoke at the same time.

The Doctor's eyes remained locked on Professor Snape's. "Stay out of my head, or you'll see something that even you can't handle," he growled.

"Professor Snape! That is a gross violation of his privacy, not to mention extremely rude!"

"I wanted to make sure that this wasn't some kind of insane plot cooked up by that raving maniac and the Dark Lord." Professor Snape spoke calmly, without inflection. "In case you have forgotten, Professor McGonagall, we are in a school filled with children."

"I have not forgotten, Professor Snape, but that still does not give you the right to break into anyone's mind. Whatever our enemies may do, we must not sink to their level." Professor Snape did not deign to reply to this. This response, or lack thereof, rather infuriated Professor McGonagall, who proceeded to begin to lecture him, as she would one of her students, on the ethical use of magic. The ensuing argument had the small effect of allowing the Doctor to leave the room unnoticed by anyone.

It did not take them too long to notice the Doctor's absence. Had anyone been there to see it, the search of the castle that followed would have been long remembered as the briefest and most comprehensive search of the castle since the infamous Spellotape Incident of 1976, which James Potter, Sirius Black, Peter Pettigrew, and Remus Lupin would each claim to their dying breaths to have had absolutely nothing to do with. Finally, when they had given up and resigned themselves to telling Professor Dumbledore everything that had happened, they found the Doctor sitting in the Headmaster's office, unsticking two sherbet lemon candies.

The two professors were mostly, although not entirely, relieved by their discovery. Because the Doctor was sitting in the office alone, both Professor McGonagall and Professor Snape immediately realized that he must have entered the Headmaster's office after Professor Dumbledore, Harry Potter, and Sirius Black had left to go to the Hospital Wing. Therefore, Professor Snape immediately inquired what the Doctor had been doing before going to the Headmaster's office; whether he had rifled through any of Professor Dumbledore's things, other than the candy bowl; and if he had gotten into any trouble.

"Me? Get into trouble? Never!" The Doctor grinned, "I was just checking on my Tardis, that's my timeship, she's been a bit lonely, all by herself all these years."

Professor McGonagall treated the Doctor to yet another of the variety of meanings of her raised eyebrow. "If your… timeship is at Hogwarts, why stick around? What do you want in Professor Dumbledore's office?" Now, she treated him to a severe stare, one which would have made most wizards and witches cower, and it was to the Doctor's credit that he did not do so.

He did give her a response, although it was a slightly meandering one, as was his wont. "Thought about just heading out, but figured I'd say hello to Albus before I left. He's an old friend, helped me out with a little problem involving a bunch of Raxacoricofallapatorians when he was a kid. Not that I knew who he was at the time," he grinned, "certainly felt a bit silly when I got back to the Tardis and realized little Al was Albus Dumbledore! Happens a lot, actually, you'd be surprised how many famous people you run into, when you're a time traveler, even if you're not actually planning to meet Shakespeare." Noticing the slight clench in Professor Snape's jaw, the Doctor returned to his point, such as it was. "Anyway, figured I'd have some candy while I waited. Haven't had any in years, Barty Crouch Jr. hated it. Who hates candy? Plus, he loved pears. I hate pears. You can always a bad guy by their love of pears, it's a well-known fact throughout the galaxy. Had to have something sweet to get that taste out of my mouth," he finally concluded emphatically.

Professor Snape was, not surprisingly, confused and angry at what he had just heard, particularly since he noticed a gaping hole in the Doctor's story. "If you met Professor Dumbledore when he was a child, why did he not recognize you when you came to Hogwarts as a student?"

The Doctor ran his hand through his hair, realizing that the two professors most likely would not believe what he was about to say, even taking into account all the fantastical things he had said to them over the course of their conversation. "…My species occasionally changes the way we look."

Professor McGonagall raised her eyebrow yet again. "Really, Doctor, you cannot possibly expect us to believe…"

Interrupting her, the Doctor said, "No, I don't, but it's the truth. Now, would you mind getting Albus? Not that I haven't loved telling you all about my life, but I've got places to go, planets to save, you know how it is." This last was said conversationally, but since the two professors were both better than most at reading others, they could tell that more any attempts to ask the Doctor more questions would end in failure.

Professor Snape, who was by this point extremely furious at the Doctor's wandering off and at his rambling, was all for fetching Professor Dumbledore, after stunning the Doctor. However, Professor McGonagall pointed out that they did not know what that would do to his alien physiology. She told Professor Snape in no uncertain terms that she was not going to help him explain to Professor Dumbledore why there was an alien bearing a striking resemblance to Barty Crouch Jr. dead on his office floor, especially when that alien was apparently an old friend of the Professor's. Professor Snape opened his mouth to argue, thought better of it, and, perhaps remembering the consequences of their previous argument, merely suggested that they use the plan they had agreed upon in the Defense teacher's office. After restraining the Doctor again, summoning Professor Flitwick to watch him, and explaining the situation briefly to Professor Flitwick, the two professors left the Headmaster's office and headed to the hospital wing to meet with Professor Dumbledore and Cornelius Fudge. The Doctor finished his candy over an enthusiastic conversation with Professor Flitwick about the time he ran into a swarm of Vashta Nerada with the witch who invented the Lumos charm.