He's Fire And Ice And Rage

"Time difference?" River suggested. She put her hands up to her mouth and shouted a hello. All she heard was her own echo. "Maybe the people are out of synch with us? I heard something like that happened to you, once, and no. That wasn't a spoiler." That had been an incarnation the Doctor had seen fit to share with her since he'd considered it safe. He'd probably considered this incarnation safe, too, and yet here she was.