The Doctor shoved his hands in his pockets and leaned back. He looked thoughtfully at Donna as she guided the TARDIS away from the alternate universe. There was something about a Time Lord – Human metacrisis, something important, something that was nagging at the back of his mind. He closed his eyes and tried to remember what it was that was worrying him. When he opened his eyes he found himself looking at Donna's chest and he realised just what it was that the little voice in the back of his mind had been trying to tell him.

"Donna," he exclaimed, "you're a woman!"

Donna looked down at where the Doctor was staring. "So I am, give the boy a pony."

That was it! Donna was a woman! And a Time Lord! A female Time Lord, the one thing that had been missing from his cunning plan to repopulate Gallifrey.

"Er, excuse me." He scurried past Donna and headed in the direction of the lab. First things first, he had to stabilise Donna's brain. It would be quite hard to convince Donna to bear his numerous Time Babies if her head exploded.

It was probably going to be quite hard to convince her anyway.

If the Doctor had thought it through then he probably wouldn't have propositioned Donna while they were both strung up by their ankles and being dangled over the pit of giant, bad-tempered and hungry spiders.

"But we saved your village." Donna objected.

"We want to help you," shouted the Doctor.

"If you kill us it's genocide!"

"And we haven't even started repopulating the species yet!"

The Doctor guessed that Donna wasn't wild about the idea when she started giving the locals instructions to drop them into the deepest part of the spider pit.

"It'll be brilliant. Just think about it, we'd have brilliant babies you and me." Just when Donna did seem to be considering it the Doctor shot himself in the foot by carrying on talking. "They'd have my brains, and my good looks, and my hair. Oh, my hair!"

"And what, exactly, are they going to get from me?"

"Oh, don't worry there's things we can do to make sure that you don't pass on any of your human DNA."

There was a resounding crack followed by a stunned silence.

"They could get your right hook," said an admiring sounding Doctor.

"You wouldn't even have to be pregnant with all of them. How about you carry half of them and I'll carry the other half?"

"Or how about you carry all of them-"

"Ok."

"And you have them with someone else."

"Donna..."

"Your family would love it. Wilf would make a great great-Grandad. Great great-Grandad, eh? See what I did there?"

"What about mum?"

"Oh. I'd forgotten about Sylvia."

"I'll be a really good dad." The Doctor thought that if he could somehow convince Donna that he wasn't an irresponsible wanderer who came out in hives at the mere mention of the word of the word domesticity then she might somehow become more amenable to his idea.

"You can't even look after a plant."

"That's a scurrilous lie; there are lots of plants in the TARDIS."

"I know," said Donna, "one of them tried to gnaw my arm off this morning."

"I'll have a word with her. See, I'm a firm disciplinarian."

It occurred to the Doctor that he'd been putting the cart before the horse. Or the offspring before the shagging to put it more bluntly.

"Just sleep with me, just once, and if you don't like it-"

"If I don't like it, you'll give up on this bloody daft idea of us having kids."

If you don't like it there's always IVF, the Doctor had been about to say but Donna's repeated physical assaults upon his person had taught him isome/i self control. "Sure," he said instead.

The Doctor lay back, basking in the warm afterglow. "Well, I think we can call that experiment a success."

Donna frowned and rubbed underneath her breasts. "I didn't know it was actually possible to pierce your lung with somebody else's rib."

"And just think about it," said the Doctor almost certain that Donna's complaint of serious internal injury was exaggerated, if not completely made up. "You could be pregnant already."

"Oh please, Dumbo, in what species can you get pregnant doing what we just did?"

"Time Lords," the Doctor answered with a post coital smirk.

"Doctor," said Donna.

"Donna," said the Doctor. "I suppose you want to know why I'm lying under your bed in the middle of the night clutching a syringe."

"Yes."

"Well, I certainly wasn't about to steal a sample of your DNA while you slept in order to breed a legion of small, ginger Time Lords."

"Oh. Good to know."

Donna was sitting at the kitchen table drinking coffee; on the table was a small potted cactus.

"Haven't seen you for a while," more than that the Doctor had the sinking feeling that Donna was avoiding him. "What have you been doing?"

"Just the usual, I phoned gramps, had a bath. Oh, and I transferred my Time Lord consciousness into that cactus."

"You-"

"And don't ask me how I did it because it's all double Dutch to me now."

"But, why?"

"Well, I was a bit sick of it really. I was starting to sound like you; I wanted to slap myself half the time. It was getting confusing. So if you want to mate with anyone, try the plant."

And with that Donna downed the last of her coffee and strode out of the kitchen. The Doctor looked enquiringly at the cactus.