The Doctor lay on his back on the TARDIS floor, one hand behind his head, and stared up at the ceiling. He was in a mood, which was not at all enhanced by the imminent departure of his friends. He'd wasted little time between the decision to make them go, and coming back to Earth. It was the right decision, but the TARDIS would be quiet without them, and empty, and the Doctor would be alone.

Many things about this were not good.

The problem, the Doctor observed, was that wisdom had diminishing returns. After the first hundred years or so, things got a bit runny in the morality department. Acts that were unquestionably evil in their time could become good—or at least the foundation for good and important things—if you waited long enough. This could warp your perspective. In his darker moments, he wondered if the longer you lived, the more warped you got.

The Doctor had been alive for a very long time.

On the other hand, he would never get older the way Amy and Rory had. The idea of staying in one place gave him the creeps. He'd never do something just because it was sensible. Morality, curiosity, courage: these were motivations he understood. He wanted to be deeply involved in everything. He wasn't like Rory. If he'd lost thousands of years, he'd turn the Universe over to get them back. He wouldn't be able to rest. He'd need to know.

Decades of observation led the Doctor to believe that this was the fundamental difference between him and most humans. Rory and Amy could settle. The Doctor just shifted.

The wisdom of ages and adolescent restlessness were a dangerous—all right, potentially apocalyptic—combination. It needed management. This was just one of the reasons the Doctor didn't do alone anymore.

Of course, it was also terrifically dull.

A shadow loomed over him. It was Amy Pond with a backpack. "Sulking already."

"Just thinking about how peaceful it will be with you lot out of here."

Amy scoffed. She sat down near his head, her expression saying that she would not be teased. "I still don't understand why you're making us leave so soon."

"Overdue library books," said the Doctor. "Have to rush them back."

"You're going to investigate, aren't you," said Amy. She leaned forward like they were in on a secret. "You should take us with you. We helped this time, didn't we?"

They had. Both of them had—if only they knew how much. The Doctor remembered everything. They were new memories, but solid and sure. Never mind what he had said to Rory; the Eighth Doctor could never have become the Ninth Doctor if Rory hadn't been there. Only a mystery like that could prod the Doctor back into the universe, and the resolution of one of the Doctor's oldest conflicts could only be a good thing. And Amy had helped up scare another piece to a very strange puzzle. It was a nice big corner piece, too. For the first time, he thought he might be able to catch a glimpse of the big picture.

Now, the Doctor thought he could stop Rory's long, strange past from following him home, which had an appealing symmetry if you thought about it.

"Is it too dangerous?" said Amy. "Is that the problem? 'Cause we're not afraid." She turned her head so the Doctor couldn't look her in the eye. "I mean, we're afraid, but we're not cowards."

"I know," said the Doctor. "That's the point."

"That's the point," Amy echoed. She frowned and squinted. "What does that even mean?"

"You'll have plenty of time to work it out," said the Doctor. He heard Rory come down the stairs. The Doctor squeezed Amy's hand got up in one energetic leap. He put one hand on the TARDIS to steady himself. "But not too long. That's a promise." He met both Rory and Amy's eyes in turn. Rory was also carrying a backpack. For once he looked eager to be off.

"It is twenty-eleven out there," said Rory, a bit anxiously. He pointed at the door. "That's a two, a zero, and an eleven."

"Have a little faith," said the Doctor. He patted the TARDIS control panel. "She's a lot more reliable these days."

"London," Rory repeated. "Twenty-eleven."

"I'll only be eight weeks, maybe ten," said the Doctor. "If you really want to know what I'm up to, look for me in books." He winked at Amy. "Rory, that key will run a lot longer than two months, but I can't guarantee that it will keep working the same way. You might get some bad dreams." There were some other things that could happen, but the Doctor didn't think they were very likely and saw no reason to alarm anyone. "Just think happy thoughts. That's what I do."

"Right," said Rory. He started to say something, then decided not to. Instead he shook the Doctor's hand. There was hesitation there, but no anger. Rory didn't do grudges. It was one of the things the Doctor liked best about him.

"See you," said Rory, though he didn't seem too thrilled about the prospect.

The Doctor grinned. "Count on it."

Then Amy hugged him, which was very nice. "Stay out of trouble," she said. "And come back, okay?"

"I always come back," said the Doctor. "Like a bad penny."

Though, to be honest, the Doctor had never had a bad penny turn up more than once.

Amy stepped away sniffling, but when Rory took her hand, she looked at him with perfect trust, so that was all right.

When they left, they didn't look back.

###

The Clockworks displaced time. In its diminished size, it didn't do much but tick across the Doctor's palm, but it felt a lot heavier than it should, and where it had crawled it left a red mark. He set it on the dashboard.

He remembered the tank's empty control room. Amy had made up a lie good enough to get them to the next step, but that wouldn't hold forever. Someone had been there, and when you had as many enemies as the Doctor, invisible ones were merely the start of the list. He would have would would have to think about that. In fact, he would have to do something about it. Soon.

Meanwhile... from one of his other pockets he took a small scrap of paper. It did not displace time, but it was displaced in time. A con artist named Patrick Belkin had given it to the Doctor when he was in Stormcage Prison some days ago. It said, I saved him—meaning Rory—now we're even. The only problem with that was, Patrick Belkin didn't owe the Doctor anything. They had never even met face-to-face.

It was high time to get that sorted. The Doctor unfolded the paper and licked the back. It tasted of mostly of prison—ech—but also of 1740 or so, in Earth years. Florida, if he wasn't mistaken. Colonial Florida. Yes. Brilliant.

He rolled a blue globe and pressed a red button.

The world turned, and everything changed forever.

###

Amy put her head on Rory's shoulder and hooked a hand on his elbow.

They had landed in a narrow alley in an old part of the city. There were roundhead cobblestones under their feet, and stone arches over their heads. But it was OK, because Amy could see plenty of satellite dishes. From one of the flats above, she heard a television. And it felt like 2011. It was kind of like how you knew you were in your own house. They were home, and they were ahead of their younger selves; everything was in order.

The couple stepped out onto the pavement. The street opened up in front of them, and they saw modern cars and people talking on mobile phones. There were skyscrapers and crowds and billboards. The air was fresh and cool. It was very early spring. For once in the Doctor's life, he was right on time. Maybe he was getting more reliable.

Rory groaned. Amy looked up and laughed.

The sun set behind the Eiffel Tower.