"I know of you, Detective." This man doesn't look like the Sherlock Holmes he's familiar with, but Aziraphale has been in the Nexus long enough to know that people don't always look as you think they might when they're coming from another world. That razor sharp analytical wit is certainly the same, and that's good enough for him.

Would it be weird to say that he's read all of the books he's in? Yes, probably. He'll keep that to himself.

Aziraphale does not get the reference, either. Crowley has been slowly introducing him to modern film and television, but Doctor Who has not made it on the list yet. Shame, that. Aziraphale would really like the Tenth Doctor. "I've never been a child, but it does evoke a sense of wonder, doesn't it? I've spent entire days in here. I'd spend longer than that, but I have a partner who drags me out if I'm here too long."