Ok, I've only seen the movies briefly and read too much fanfic; if I'm horribly out of continuity or something, just assume it's AU or an effect of time passing. This appeared in my head and demanded writing. There is CHARACTER DEATH implied, from old age.
It had been easier than he'd expected, convincing his current nurse to leave him alone in the workshop, even just for the twenty minutes he'd been promised. True, his condition was poor enough these days to require near-constant monitoring, but the day JARVIS couldn't track his pulse rate and respiration...
He sat back in the chair he'd designed himself (not built, sadly, his body couldn't handle the force required for machining by that point, but JARVIS and the bots were more than happy to help their creator; well, not happy, not really, since it was a concession to his weakening, but willing) and waited to hear the quiet click as the door closed behind him. He smiled softly, and called breathily, "Daddy's home."
The family had expanded over the years; eight self-aware creations came towards him, speed carefully contained but still radiating joy over their sorrow. JARVIS knew, knew what the medical records said, knew what his creator knew, that this was likely to be the last time he'd be able to see them, and that knowledge would have been shared around for this one meeting.
His hands shook when he lifted them these days, but he reached out carefully, slowly, to meet the bots as they reached for him. Robotic variations of hugs, a final connection to the source of their little clan.
He'd lost track of time when a mechanical noise he'd never heard before began, whirring over the sounds of cheeps and clicks and whirrs from his children. He looked up, slowly, confused at the distortion gathering in the center of the shop. "JARVIS? What-"
"I am uncertain, sir," came the response, and he felt the squeeze in his heart at the AI's obvious confusion (this is my family, my children, and have I done enough for them?), "but it is broadcasting our safety."
Broadcasting the signal that they'd agreed upon years ago, the one that marked a completely clear, and above all safe, transmission or object or person. The signal that no one else knew, that no one else even knew about.
And it was broadcasting from a- blue...box. Which opened. And a stranger exited, smiling. And while he was trying to comprehend this, the stranger- began greeting the bots. By name.
"Who?" he breathed, too tired (and old, but when boxes and British men in strange clothes just appear in your home, age is really just a number) to be more than mildly concerned.
"Oh, sorry. I'm the Doctor," the stranger said, as though that explained everything.
"My doctors tend to knock," he said dryly. Never let it be said that infirmity affected his mind.
The Doctor grinned sheepishly. "No, no, I'm not a doctor, I'm the Doctor, and well, I owe a favor and really, you know you're curious about the box and how I got in and just why JARVIS isn't throwing a fit just now, so come on then!"
Somewhere in the middle of that the Doctor had taken control of the chair and propelled him towards the half-open door. Before he could even begin to object, they were inside, and the man was closing the doors behind them and leaping for a complicated console area in the center of the- impossibly large room. Seriously, this was huge, there was no way it all fit in that little box, which meant that it wasn't so much a box as a doorway and probably like a portal of some kind, and when had he started muttering out loud? Because it was either that or the Doctor guy was psychic, because he was grinning madly and congratulating him on his observations.
"She's my ship. The TARDIS. She's- well. My everything."
And he felt it, felt the overwhelming presence behind those walls, in the very air around them, this was a ship, yes, a world inside itself, but it was also alive, and oh, if only he'd been able to do this for JARVIS...
"Your ship and my AI would have beautiful children," he whispered, and smiled faintly as the Doctor laughed gleefully and the presence around him warmed.
"Maybe, you never do know," and with a few clicks and levers the sensation of movement shivered to a halt. The Doctor whirled away from the controls and came to a sudden stop directly in front of him, startlingly serious. "I said I owed a favor, and I do. Not to you, not really, but you're the biggest part of the payment. Although I think it's for you, also. But first I need to explain-"
And this was too much, this was impossible again, but so were Norse gods and shapeshifting and flying metal men, so he simply accepted it as the Doctor explained time and space travel, and avoiding paradox, and saving worlds, and a university, an enormous scientific research world 20,000 years in his future, the only one of its kind, begun to show that created minds were not to be feared simply on principle, to broaden definitions of life and person-hood, and while his mind was still wrapping around this they exited the TARDIS into a paneled hallway, warm and inviting and full of shining metal and ohgod impossible this couldn't be possible-
"Hello sir," came that familiar, wonderful, impossible voice, and he couldn't have sworn if the tears were in that voice or in his eyes, because here was his family, his children and their children, and they were so alive, thousands of years after he was gone, here was his legacy. "It's" and a hitch, a nearly inaudible pause "so very good to see you."
And of course it was, who or what else could it have been, and he stretched his hands out again, to touch his children again, to reassure them that they had gone so far above and beyond everything he had hoped for them, to tell them he was so, so proud and so happy for them...
His failing body forced the end of their reunion sooner than he would have liked; who was he kidding, he would have stayed with them forever if he could, and really, he could, he had, they still remembered and they taught their children about him and ohgod it was a kind of immortality to live within them.
"They helped me save a world," the Doctor said while his ship carried them back and supported his faltering strength. "They helped me and when they couldn't travel with me I offered to bring them something. He asked for you, blurted it out before he even thought, and the others were so hopeful that I didn't think you would mind."
"Parents always want to know that their children are ok," he murmured, halfway beyond sleeping, only barely seeing the Doctor's slight twitch at that, feeling a momentary stab of guilt for having hurt this man who had done him the greatest kindness anyone ever could; feeling a moment later the TARDIS reaching out to comfort both of them.
That comfort carried him back to the center of the workshop and through the disappearance of the box. It countered the lethargy he felt creeping up, and he didn't feel a need to chase it down this time. "JARVIS?" he spoke softly.
"Sir?" The realization was clear, and the sorrow and resignation.
"It's going to be ok, you know. You're all going to be so amazing."
"Thank you sir. And-" if he'd been human, he would have swallowed hard, or held back a sob- "you always have been."
He heard the monitors begin their alarms, then silence, and smiled softly as JARVIS cradled him down, as his children, his family, joined around him as he slipped away to thoughts of a legacy crafted in shining steel.