Gödel's incompleteness

Prologue

Setting: DW - roughly before "Planet of the Dead"; HP - throughout the life of Barty Crouch Jr.

Disclaimer: I own neither Harry Potter nor Doctor Who. Also, I apparently don't own any clever or original disclaimers.

1994 (3) A

Branches in his way, darkness in his view, and yet he kept on running – because that was all he ever did.

And there is was again, the screaming. It made him only run faster, but not quite fast enough. Again and again, sounds of sheer terror and agony echoed through the woods before he finally reached their origin. On a small clearing amidst the trees, illuminated by a glowing skull in the sky, a woman lay sprawled on the floor and was whimpering loudly. She must have tripped on her escape, over what looked like a fallen statue. But he had no time to further evaluate the situation as he saw another figure approaching her in long menacing strides.

His jaw tightened and he hurried towards the scene. Regardless of how little he understood the situation, there was only one thing he could do at this point. "Stop this right now!" he yelled and took a firm stand between victim and aggressor.

As expected, the man slowed down. "Out of the way, scum," he hissed icily and raised his arm, holding some kind of pointy, wand-like weapon.

While he had expected to be threatened, the Doctor had definitely not foreseen a reply in a voice that was his own.

This was wrong.

"I won't let you harm any more innocents," he replied firmly. Because he would always protect the weak. But not because he understood why the silhouette he could make out in the faint moonlight resembled his own far too much for his liking.

This was so very wrong.

A dark chuckle escaped his opponent's lips. "Innocent?" he laughed, and laughed, and laughed.

Breathing heavily at the sheer impossibility of it all, the Doctor glared at the man. "Innocent until proven otherwise," he ground out and finally released the question that bothered him the most, "How can you be me and not understand that?"

Eyes that were his own returned his glare all too readily. "It is you who understands nothing," his double hissed. No…not a double. He was literally speaking to himself. A blondish, leather-clad version of himself, as he could vaguely see now. But worst of it all, this was what he would become. His future self, striding closer with a mad glint in his eye and a nervous twitch in his mouth, was deliberately ignoring the horrible paradox he was about to cause. "Tell me, Doctor," his other self whispered and placed the tip of his wand against the Doctor's chest, "If I kill you here and now, will it make a difference?"

Finally remembering to breathe, the Doctor took a step back. Thankfully, the woman had fled in the meantime, but this…

He raised his sonic screwdriver in defence. "It will and it won't, you know that," he retorted angrily. Had his older self even forgotten the basic principles the multiverse? He himself would die, but that would change nothing about his other self's past. Still, it would be one of the stupidest moves to make, for reality itself would bleed.

Just as he had finished that thought, a sharp pain shot through his back, forcing him to his knees. "You…can't be serious," he panted, feebly trying to get back to his feet.

And for the first time in their conversation, he saw counterpart's face softening. "You know, you might end up wishing you'd died here tonight," he whispered.

And the world went black.

A/N: Well, there we go. The prologue of a story that has been ghosting around my brain for nearly a month now. I feel like I should write an actual chapter full of remarks to this fanfiction, but I will just try to summarize the, err, warnings right here and now.

I greatly enjoy crossovers between Harry Potter and basically any other fandom I happen to find myself in, and David Tennant's involvement in both the Potter- and the Whoniverse is just too tempting to ignore. The Doctor and Barty Crouch Jr. sharing one appearance is often explained via the chameleon arch, memory loss or doppelgangers, yet I could not help but wonder: what would have to happen for the Doctor and Barty Crouch to actually be the same person?

Considering that motivation, please be aware that this is, basically, an experiment. I think I came up with a pretty nice explanation, but, ah, I'll just let you decide on that once I get around to actually uploading all of this.

In any case, please prepare for...

- Drama. The Doctor will be, in a way, living through major events in Barty Crouch's life, after all.

- "Science". Timetravel. And basically, well, a hopefully annoyingly twisted, timey-wimey plot.

- Creative freedom. I did some background research, but if I had the nerve to mind every detail of the Potterverse, I would not even have started writing this story. It roughly follows...some events, but beyond that, I can't guarantee anything.

And last but not least:

- A horrible experimental structure! :D The story is arranged in four sections, all of which deal with a different aspect of the Doctor's life in Wizarding Britain. So basically, you'll be reading about the same events four times from different angles, but only get the full picture in the very end. As if time travel wasn't bad enough already :D
However, you'll still be able to read the chapters in another order. The years are given in the chapter titles, with the number in the brackets implying the order of the chapters taking place in that year. The letter at the very end mark the Doctor's subjective timeline; following the alphabetical order primarily and the chronological one secundarily will produce the story in the traditional order.

But that would be boring, wouldn't it? :D

So the preamble got awfully long after all, but if it did not scare you off: welcome aboard!