Usually a call will do it. Except for a short while, a call couldn't do it, so Aziraphale had gone to lengths to attempt to bring him here. But that was all in the past, and he had shown up back then, and he had shown up now, and Aziraphale was pleased to have him a ring or a few halls away.

He wrinkled his nose to the suggestions. "They'd do more harm than good. And, yes, I know, they're demons, they don't do good, but I don't trust many with the safekeeping of books or my things. I'd hardly trust an imp. They seem rather prone to mischief."