There is, as you know, a good number of Good Omens Fanfictions, RPs etc in which the author/artist muses about what would have happened if Aziraphale and Crowley's roles were swapped. This is the so called 'Hellstream''s take on the idea of what Aziraphale would be like if he would have Fallen
Wow, what I love best is how the suit and wings suit (heh) his shape so well! I think that's just the sort of little touch that makes a roleswap awesome.