Disclaimer: I own some Doctor Who merchandise, but I have no claim of ownership to the copyrights of the franchise. This fic is canon-compliant, which means it does not directly contradict any aspect of canon.
As a tall, wooden box suddenly appears on a street corner in a quiet London suburb, an old man in a red wool hat comes out of a nearby house. "Doctor!" he shouts excitedly, running toward it. "Doctor!"
The door on the front of the box opens and a younger-looking man sticks his head out wonderingly. "Yes?" he asks.
"Doctor," the old man pants, coming to a halt beside him with his hands on his knees. He looks up after catching his breath, but seems uncertain now as the other man doesn't appear to recognize him. "Doctor?"
"Yes," he says again, puzzled.
"Oh!" The old man smiles broadly. "Oh, it is you! Of course it is, I'd know that blue box anywhere. But look at you!" He pauses before chuckling, "Quite a difference from last time."
"Last time?" the man in the box asks as he steps out, pulling the door closed behind him. "You've seen me before, then?"
"Doctor…" The old man puts a hand over his heart, looking hurt. "You mean… you don't remember me? I thought you said you would still have all your old memories and things when you'd regenerated…"
The other man's eyebrows shoot up at that statement. "Regenerated?"
"Yes, you said that when you–"
"Stop!" he interrupts, turning back to the box with a key in his hand and reaching for the door. "I need to leave."
"But you just got here," the old man starts to protest.
"I know, but I can't…" Closing his eyes and sighing, he says, "I haven't met you yet. You might know me, and if I've told you about regeneration then you must have earned my trust as well, but I do not know who you are right now. I will meet you in the future, though I don't know if or when you'll see me again; things don't always happen in the right order with me – that's the way it is with time travel – but, if this is the last time for you, there is one thing you can do for me: just… just carry on and be fantastic, alright? Can you do that?"
"Of course I can," the old man replies, saluting him. He watches with misty eyes as his hero disappears into that amazing box of his without looking back. Standing off to the side as it vanishes, he drops his hand and looks up at the sky as he continues, "You know, Doctor, I don't care if you're wearing pinstripes and trainers or a black leather jacket; Wilfred Mott is always at your service."
A/N: This fic is part of my CC'verse (see my profile for more).