As the Tardis faded away, The Doctor held me close. He wasn't the real Doctor, of course, but he was my Doctor. At first I struggled to come to terms with this. It was strange leaning against his chest and hearing only one heartbeat. But over time I became used to it. He was, after all, still the same person. The things he said still made no sense. He still spoke so fast you needed to record him and play it back at half-speed to hear any actual words. And he still annoyed my mother to no end.
Without a Tardis, we dedicated ourselves to fixing things, The Doctor and I. He enjoyed his work, but I could tell he missed the freedom of having the universe at his fingertips. I know I did. Still do, even though by now I'd be far too old to enjoy it.
It's been weird, watching The Doctor grow old. His isn't the kind of face that should be wrinkled with lines and blemishes. It kills me to see him struggling to walk. He still possesses his maniacal energy, but his body can't keep up anymore. We both know our time is coming, and in a way I'm glad. Seeing The Doctor so trapped is more painful than you could ever imagine.
When we were younger, we travelled this alternate universe constantly (although we could never leave this planet), discovering new places, mending ancient electronics, keeping an eye out for alien activity. But we never saw any. I was always scared to let The Doctor out of my sight, just in case he disappeared and left me stranded here again. But gradually I came to realise he wouldn't do that. He couldn't. He had nowhere else to go.
We never had any children, although I think he wished we did, but looking after my baby brother was enough for me. We told him stories of our adventures, and he fell in love with the Tardis as much as anyone who had actually travelled inside it. It hurt The Doctor to speak of his Tardis. She was his first and only love for a long time, and in a way I was weirdly jealous of her. I had to keep reminding myself she was only a blue box.
As our time draws nearer, I am writing down everything we ever did, and everything that happened, so that future generations will know who he is and what he is capable of. He is out there, and he is still saving the universe more times than you can imagine, even though at the same time he is here, in my arms, slowly dying with me.