You're the Only Prayer I Need (джен)

Crowley had, in the six thousand years Aziraphale had known him, shed his skin exactly twice that Aziraphale knew of. Both times he had disappeared without a trace, having retreated somewhere very safe and very, very unknown to hide while he was so vulnerable, and Aziraphale had never thought to ask beyond that information. Everyone was, he had supposed at the time, entitled to their secrets.
The problem was that he had stumbled directly into this secret now, and there was hardly a graceful way out of it.