Constant

The Doctor had expected the main room of the TARDIS to be empty; insomuch as time mattered here, it was 'late' by human standards. His two companions ought to be sleeping—and yet there was Rory, sitting alone on a step and looking unusually contemplative.

"Got a lot on your mind?" he asked to break the silence, but when Rory looked up his eyes were distant.

"Yeah," he answered, sounding distracted. "That's the problem."

The Doctor said nothing else, walking over and sitting down next to his friend on the step. He waited, knowing that Rory would speak again when he was ready for it. Ever methodical, ever careful.

"Humans," Rory began at last, "they're not supposed to live much longer than a century, at the very most. What does that make me?"

"A perfectly normal, thirty-something human."

"With a brain full of over 2,000 years worth of memories," Rory insisted, looking over at The Doctor with true focus for the first time. "I can keep them locked up most of the time, but they're always there. And I'll never be able to get rid of them." He sighed, sounding wearier than The Doctor had ever heard him before.

"You do get used to it, Rory," he tried to assure his friend. "It just takes time."

"And that's the problem, Doctor," came the hollow reply. "Time is the last thing I need more of right now. How am I supposed to carry all of that around with me? How is it ever going to feel any lighter?"

Rory shook his head and looked over at The Doctor again, and this time his eyes were imploring.

"How do you handle it? How has it not made you absolutely mad by now?"

The Doctor felt his hearts lurch in the silence that followed, recognizing all-too-well the pain that he could see in Rory's eyes. It was the same pain that haunted him every day: the pain of outliving so many people you cared about, of having to bury all of your friends and having to wonder who would be there to lay you to rest when your own time came.

"Do you know what it is," he asked at last, "that I find so incredibly amazing about humans? It's that you're still around today. Think about it, Rory. Think about all the time your species has had to tear itself apart, to get swallowed up by pride and vanity and war.

"And you do realize what it means that you never got swallowed up, don't you?" he continued. "It means that your impulse to love and protect one another was stronger than your desire to hurt, or to kill. And that, Rory… that is a very rare thing in this universe. It's the same thing that kept you sane for those two long millennia, watching over that box."

"But how is that supposed to help me forget, Doctor?"

The Time Lord bit back a sigh, shaking his head.

"It's not," The Doctor answered. "It's supposed to help you remember. That impulse, that love… the memory of that is what will keep you human. That's what will keep you sane, when all you want to do is break down. That's the most important constant in existence. You can never, ever let yourself forget whom you love, and what that love feels like. You can't let those bonds be broken: not by time, not by space, not by anything.

"Why do you think I never travel alone for very long?" he finished quietly, looking suddenly melancholic. "That makes it so much harder to remember."

Rory was silent for a few moments, letting the weight of his friend's words sink in.

"You've still got us, Doctor," he said at last, clapping a comforting hand on the Time Lord's shoulder. "Whenever you call, you know we'll answer. It's the least we can do, really."

The Doctor smiled, returning the gesture with his own hand.

"You really are something else, Mister Rory Pond. Thank you."

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A/N: I think Rory Pond is an absolutely amazing character, and I could never possibly write enough things testifying to that effect. I hope you liked this little drabble!