Oh, this is fantastic! A sweet and hot new story as well as a great homage to the original. :D

Aziraphale had spent six millennia not thinking about saliva without difficulty,

This cracked me up so hard...and I realized why later, it reminded me of a Peanuts strip I read when I was a little kid, with Linus (IIRC) going on about being aware of your tongue and how once you were, you couldn't stop being aware of it.

Anyway, I digress. Loved the mix of funny and sexy and sweet.