Was that the wrong thing to ask?

"Oh, that sounds like me and Lan Zhan!" he grins. "I used to cause him so much trouble."

Well, he still did. Almost constantly. And poor Lan Wangji got assigned to be his babysitter while he wrote lines or did menial tasks. It was a wonder he still wanted to talk to him after all that. Crowley, on the other hand, hadn't struck him much as the troublemaking type, but maybe that too was in his younger years.

"This one time, we-" he started, only to have his eyes drawn to the dark flute in Aziraphale's hand, complete with vibrant red tassel. On instinct, he reached for the one he carried, tucked into the back of his belt, but it was still there, still whole, and he withdrew it slowly, holding it up with a lopsided smile.

"You drank... oh, so... you can use demonic cultivation?" he blinks in surprise. The possibility must exist, if his other self had seen fit to lend him Chenqing. Though... with little explanation, apparently.

"It's for channeling. It makes commands easier to understand for-" how did you nicely say an army of undead, "whatever you're controlling."