A Doctor Who and A Wayward Family Adventures (Fiction: Doctor Who / Supernatural Crossover)

[Multiverse Learner 101]

...Let's start from the very beginning.

It was around the year 1983. A tragedy struck a normal, suburban family. The Winchesters. They were your typical average folk here in Lawrence, Kansas. At least, that's on the surface.

One could hear the sirens in the distance, where a man looked from afar as he looked passed the police cars and fire trucks that arrived to survey and put the fires out of the burning house. A man called the Doctor. No, not a man, but something that cannot be from Earth, of any sort. Quite short in height and looked Scottish. His eyes were blue, though the man could change such colors anytime he wanted for good calculated measure. He wore a wrinkled cream-coloured linen suit, with a glistening silk shirt worn with a green silk cravat, and a paisley-banded white fedora.

Where to begin? Where to end? The Doctor could remember like it were only yesterday within time. He remembered. His last incarnation, the one with the ridiculous rainbow coat, was where it all truly began for him, when he crossed paths with a family of hunters called the Winchesters. The way he meets them is out of sync, from here to there. The Doctor, as of his incarnation of now, is the dastardly planner and mathematician of probabilities that he is, would find himself looking at the day, or the night, where it all began for the Winchesters.

His eyes looked at the huddled family nearby, a favored Impala, of the grieving father John, of the much younger Dean, and of the little infant Sam. The time of innocence ended in one fell swoop.

The Doctor's hand twitched within his umbrella, which he held too tightly. Why? Because he couldn't help but glance to his left. His eyes narrowed. From afar, somewhere in the deep woods of the forest, he could truly see what lay underneath the shadows. A man, standing from afar, like a predator stalking its prey, but not pouncing yet. Pale yellow eyes. Walking around an anonymous human meatsuit, long dead by prescription, from what the Doctor had judged in terms of specifics. A so-called yellow-eyed demon.

The Doctor mused a little, with a dangerous edge of a smile. "Of course you'd still be here." He muttered under his breath.

The yellow-eyed demon's glare looked straight at him, cautious and cunning, before quietly retreating somewhere else. Typical. The wolf runs away, plotting and scheming.

"...Always on the run, that one," says one unknown man's grim voice, which was also a bit Scottish. Or was it Welsh?

The Doctor looked around and... frowned. No, not frowned, unexpected, his mind couldn't even calculate in more dimensions when looking at the person standing in front of him.

He looked taller, with large brown eyes, wearing a black suit with a white collar, wrapped in a black necktie. There was also the navy black trenchcoat that he wore, which had around five silver stars on both shoulders, like he was some kind of general. But it's not his appearance that made the Doctor pause. No, it was something too otherly. He can't see him. Not in the sense of the physical. No, the metaphysical. Like he did not belong in Time, but from a duration that he could not decipher.

The Doctor couldn't help but take a cautious step back. "...Who are you?" He muttered, careful and grim.

"...I'm you, well, the final you," says the man who was also revealed to be the Doctor.

"Final you?" The Doctor, the number seven, muttered the words carefully. This was unprecedented. A future version of himself? But from where? Or when? More to the point, how come he can't see him?

"Well... sort of," the other Doctor, an unknown one, walked towards him with his hands tucked under his pockets, his voice was grim yet measured, like it was timeless. "Not really the final incarnation of the first regeneration line. Oh no, that would come later, if ever."

"If ever?" the Seventh Doctor narrowed his eyes and sharply offered a rebuke. "I never thought I'd be callous enough to reveal my own future."

"Yeah, well, that's the thing," says the Unknown Doctor, looking at him with a measured, pointed look. "It doesn't really matter what I'd say, because the future's changed."

"What?" the Seventh Doctor looked cautious.

"You heard me," the Unknown Doctor spoke grimly. "The future's changed, past me, it's been changed long before you met me here. It all started when you met the Winchesters all those years ago, when you shouldn't have met them. Since then, everything seems to click; travelling between our Earth and this one, no matter what timeframe, seems quite easy. Don't you ever find it odd? A completely different universe linked to our own?"

"And? We've travelled through other universes before with different modal properties; this should not be surprising to us anymore," the Seventh Doctor pointed out.

"Ah, but that's the thing, you're still thinking this is just a simple travel between one universe to another, from one configuration to another," the Unknown Doctor spoke softly, his eyes held something of a mystery of the ages. "When, in point of fact, what is actually happening right now is what I call sub-timeline travel."

"Sub-timeline travel?" the Seventh Doctor looked at him with inquiry. "I never heard of such a thing."

"Oh, but you wouldn't," the Unknown Doctor spoke with calm ease, like he was used to explaining this, and not for the first time. "Because not even the Time Lords could have known it. They've mastered all forms and modes of Time. But... they never really mastered Aeviternity."

"...Aeviternity?" the Seventh Doctor muttered with great care. "I've heard of that term before, something that's used as a term by men of philosophy and medieval culture to describe a time not of man but of other, but that is still something that the Time Lords have already done and mastered."

"No, that's what they think they've done and mastered; there's a very big difference," the Unknown Doctor pointed out carefully. "What you call mapping time, aeviternity, and eternity, are simply just degrees of Chronos, not Aevum, and most certainly not Eternity, which no one can truly take as if they were their own. As I said, the Time Lords had mastered all forms and modes of Time, which is Chronos. It's still limited either way."

The Seventh Doctor didn't show it, but his inwardness felt a sense of disturbance. Because he was hearing a future version of himself from a far future just... casually stating that the Time Lords' perceptions of time were, in fact, limited? That can't be...

"Forget everything you think you know, past me," the Unknown Doctor gently explained as simply as he could. "Since I'm here, this me, I would not rely on any chronology, because I'm not supposed to be here talking to you, this never happened in any so-called cycle, the moment I stepped in, I changed the rules, which means that the future can be changed, in a way that not even Time Lords could see coming. So all those future encounters with the Winchesters, from your point of view? I would not try to rely on that as a foundational basis for how you are to react when it comes to Aeviternity."

"...Why are you telling me this?" the Seventh Doctor spoke a little darkly, yet disturbed by such a revelation.

"Because you're one of the few incarnations of me who can grasp at least the scale of what I'm talking about. So, I'll let you ponder these thoughts within your dastardly mind and let you simply think about it," the Unknown Doctor explained, before he eventually decided to quietly walk away. His back turned against the Seventh Doctor, who looked as the stirrings within his twofold hearts remained shaken.

If what this future self said was true, then what even is Time for him? He has fought gods and demons of every sort, but this? This felt like either a new kind of discovery or a darker adventure that can test him in ways that no one has ever tested him before.

As these thoughts stretched before him, the presence of the Unknown Doctor grew too far for the Seventh Doctor to look, not just in terms of physical and metaphysical distance, but of a kind unlike any other, which would need to make him reconsider everything.

What if everything about Time was always the wrong understanding of Time?