A remarkably open and reasonable answer, and hang on did he just say brother?

"Sorry, your brother?" Grace is visibly disturbed by this thought. Angels have families now? They're not just... summoned into existence by some existential need? Are baby angels a thing?? This is powerfully stupid. Lucifer's universe, she concludes, must be very different from hers.

As if his existence wasn't evidence enough of that. Not that she'd been treating him any differently for it. Shit.