"How’d you get in here, Crowley?" asked the Doctor, after a moment of stunned silence.

"Never underestimate the King of Hell, darling," Crowley replied, giving one of those smug smiles that he was so fond of giving. "Nice bow-tie, by the way. Very…human."

"Very cool, isn’t it?" the Doctor said.

"Oh, don’t encourage him," River snapped. "Next he’ll dig out another fez."

"Oh, god, no," Amy moaned.

"What do you want, demon?” Rory demanded, sword ready.

"Calm down, plastic boy," Crowley said, holding his hands up in a pacifying gesture. "As it happens, I was invited. By the owner."

All eyes turned to the Doctor. “I certainly never…” Flustered, he turned and dashed to the TARDIS console, fiddling with levers and dials. “I’ve got shields and…stuff…to stop your kind getting in here.” He pulled the monitor in front of him, and frowned. “That’s funny, I could’ve sworn…”

"I said, the OWNER, ducky.” He patted the console, and the central column lit up briefly. Not in warning, but in welcome. “She’s a free agent, you lot are just along for the ride. All right, then, sexy. What is it you want?”

"That’s my name for her!” The Doctor pulled out his sonic screwdriver, and pointed it threateningly. “Get out of here right now, or I swear by Kasterborous—”

"You’ll what? Sonic me? Give it up, you mad giraffe. I’m not leaving until—"

Without warning, Rory thrust his sword at the demon. Crowley’s eyes went red, and all trace of a pleasant expression left his face. With one hand, he sent Rory hurtling through the air, and left him hanging on the wall. Amy took a few steps forward, and Crowley held out his hand warningly. “Watch it, Ginger.” To the room at large, he said, “You’re all lucky I’m here on invite, or else I might just have to snap a neck or two to make my point. Why don’t you give the two of us some peace and quiet, eh?”

The Doctor was about to protest, but the central column flashed again. It was less patient this time. River grabbed the Doctor’s shoulder. “Leave it, dear,” she whispered. “If the TARDIS wants time alone with the King of Hell, then she’s got her reasons.” She turned him around forcibly. “Amy, get Rory, and we’ll go into the library.”

At the top of the steps, the Doctor wrenched himself out of River’s arms, and turned to face Crowley again. “If you hurt her in any way, Crowley…”

"Guest, remember? Honestly, it’s as if you don’t trust me! And there’s nothing you can do to me anyway, Time Lord." Something silver flashed in his hand, partly up his sleeve. "I could kill you dead, properly, if I wanted to. But as it happens, you’re more useful to me alive than dead. So leave us alone. I’m sure Sexy here will call you when I’m gone."

In a muted, angry silence, the four trooped out of the console room. When the door clicked shut, Crowley pulled the angel blade all the way out of his sleeve. He dragged the tip around the rim of the console. The rasp of it pierced through the hum of the console, and echoed ominously. “I’m listening, dear. What do you want that’s worth as much as the soul of a TARDIS?”

(I wrote this ages ago in a reblog, but I thought I’d put it in my own post.)