Have you ever had the feeling something's missing, and you just don't know what it is?

You think and think, but you simply can't put your finger on it. And it's just driving you crazy, but it's just not there.

That's how I feel. Every minute of every day, I feel like something's missing. Sometimes, I almost remember it. A person, a face, a name that never quite fully materializes in my memory. For a moment, I'll almost remember it, then I'll forget again.

It's silly, I know. It's all in my head. It's not real.

But then why do I cry? Every night, in my room on the TARDIS, when the Doctor isn't listening, I cry myself to sleep. Over what? I don't know. I just don't understand it. It's like there's something missing.

The Doctor notices, I think. He's been extra nice to me lately, taking me all these lovely places. Victorian England, a volcanic island on earth with a mountain absolutely full of diamonds, Scotland during the time of Queen Mary, met a few of my favorite artists. Van Gogh was nice – offered to marry me.

I almost thought I could for a moment. And then it seemed impossible, like there was someone else I loved, more than anything else.

But that's ridiculous, of course. Wouldn't a person remember someone they fancied?

The Doctor – he's cared about someone like that, and lost them. I can tell when we see couples together. He gets this sad look in his eyes, like he's remembering something – someone. If the Doctor can live a thousand years and never forget someone like that, then I certainly can't. You don't forget a person you care about like that. Not never.

I can't have forgotten anyone like that, can I? This whole this is crazy.

But then why does it feel like there's something missing? Someone missing?

If it's crazy, if nothing is missing, then why am I crying?