The final part, written a full year after the first. Day 25 of my New Year's fic-a-thon. 6 days to go!
Donna Noble's deathbed is peaceful. Shaun sits by her side, holding her hand in his. The nurses say that she's done with consciousness, that now it's only a question of waiting until her body slips away.
And so he waits, watching his bride's chest rise and fall. They've had a good, long run, seen a thing or two. There will be time for grief very shortly, but, right now, the most important thing is to be with her for every second she has left.
"Doctor?" He simply stares. It's been long, long years since their wedding night and the voice in the dark. This is unmistakably the same voice, though tempered by Donna's now-much-older vocals cords.
"Doctor, are you there?"
He still remembers, vivid as day, what Wilf told him about her adventures, how she'd been made to forget. All through their life together, there have been moments where her face went still, and her eyes looked far, far away, and if you asked her what she was looking at, she'd say "I feel like I've forgotten something."
He's tried not to think about it too much, really. He made sure to take her travelling, to see the world, but there wasn't really anything he could offer her. Nothing to compare with other worlds and saving the universe. Easier just to let it rest at the back of his mind, especially because he hasn't heard the voice in 50 years.
"If you're listening, Doctor, then I need to talk to you. There's not much time."
He strokes her hand, waiting.
"I didn't want to leave the Tardis, Doctor. Not even a little bit. I was furious with you for ages. The dreams that we had about you! You would've laughed. She wondered why she kept dreaming about Granddad's poor friend Mr. Smith being eaten by purple monsters and used as a giant's football. I could've told her why." She chuckles.
"No, I didn't want to go. I could've stayed with you forever, and we would have been happy. Best mates, time of our lives, place to place. Still, though…I would never've met Shaun. We'd never've been married, never've had kids. That's an adventure too, you know. The kids especially. They're doing well, Doctor, both of them. You'll never have kids, will you? And I certainly would never've had yours, Time Lady or no.
"I've wandered off again. This old brain is wearing out. This old body, too, and there's no regeneration for me. I was a metacrisis, just an accident, really, and the energy faded away... I'll be gone soon, Doctor. What I've been trying to say is…I'm not sorry that I left. Not really. I'm sorry that I had to leave you alone. I hope, I really hope that you found someone to stop you. But I pushed through into Donna's mind, and I fixed her a bit, and Shaun did another bit, and the children did even more, and I've been happy. It's been a good life, really it has, and I would've missed it if I'd stayed. No telling what I might've done with you, but I know what I did here, and I wouldn't've missed it for the world.
"If you see Shaun, tell him that I love him. And…as a favor…take care of yourself, Doctor. I've missed you a bit these years."
Donna's chest rises and falls, and a little smile spreads across her face.
"You told me I was brilliant, but I finally believe it. Goodbye, Spaceman."
This is my own private headcanon. I know we'll never see her again in the show, but I really want to believe that this is what happened, in the end.