My Thief is sick. He is riddled with a strange disease that I cannot comprehend. I understand it, of course. But I have never felt it, this strange rocking madness that seems to overtake him sometimes.

There seems to be no permanent cure. It goes away for a little while, and then it comes back again.

They help. His companions help. They take his mind off the sickness; make him feel alive again. He races off, desperate to impress them, and runs headlong into some new disaster without even the courtesy warning them in advance. Not that he's needs to, recently; they always seem to know that he's coming.

But then they wander off: the pretty ones, the young ones, even the Captain. Eventually, they all leave him. And the sickness strikes.

Sometimes it's easy to subdue. There might be a distress signal or an exploding star. Sometimes, I see a possible new companion come floating through the dust of time and head for them. Other times, I have to make something up. Why is that? When all of time and space are riddled with all the problems my Thief is determined to fix, why can I never find something when he needs it most?

My Thief is bored.

That's what he calls it, this sickness. Boredom. It has him pacing my halls and tearing at his hair. He develops a lethargy, a listlessness. He sits on my steps and mopes.

It isn't right for a Timelord to mope. It isn't really fair on me, either. With all the other things I have to do – watch where we're going, listen to the universe, keep myself alive, organise his clothes, keep him away from the beginning of the universe (because he'd only do something silly like pick up a vital piece of dust on his suit and eliminate the creation of his own race) – I also have to make sure he isn't going to do something too stupid.

Which he is, of course.

He's sitting in his study with a pencil and scribbling in one of his journals. Another of his great ideas, I suppose. I'll see it soon enough, once he's done. As soon as he looks away…

And I'm right. It's another of his great experiments.

He looks so gleeful, sitting there with his bow tie skewed. His hair is a mess again. I think he's wearing his shirt inside out. With so many female companions, you would think one of them would have taught him better common sense.

He's finished it. The book has shut with a snap and he's looking to replace it on the bookshelf.

"Now, now, sexy. Where did you put them?"

He doesn't really want an answer. Even if he did he wouldn't get one. I'm not helping with this.

"Ah! Found you."

Wrong.

"Now, sexy, don't move that."

And he's off, running back to my control room, running back to a life of adventure. He'll stop before he reaches it. He can't think of anything to do.

But it gives me a moment to save him. Again.

Carefully, I reach inside the book, and pluck the letters off the page. They dissolve into the air, melt into the fabric of the universe, and are gone.

Of all the things I have to do to keep my Thief safe, my least favourite has to be, has always been and always will be, deleting his fanfiction.

It's not even any good.