Manchester Lost

Everything About Fiction You Never Wanted to Know.
"Grrr, I am evil. And you suck." (art by Quantum Witch)

Manchester Lost by JAMoczo is a very funny Good Omens Crack Fic / Action Adventure / (non-explicit) Slash Fic in which Aziraphale is captured by Hell and Crowley, War and the Archangel Michael (on a Mission from God) break in to save him and set off a second apocalypse. It introduces entertaining characterizations of other angels such as Michael, Raphael (Aziraphale's adopted father), Gabriel, and Uriel. It's a self parodying Affectionate Parody with many interesting twists and turns along the way.

It is technically a sequel to How Crowley Fell Out of Love with the Bentley (which is a sequel to Good Omens). Manchester Lost has a sequel itself, which is complete: Paradise Thwarted.

Warning: Spoilers ahead!

Tropes used in Manchester Lost include:

Uriel: I can't believe you just killed Lucifer!

Raphael to Lucifer: "And I know you have a very strong fondness for... er... sharp, pointy things, and so help me Light-Bringer but if you don't let me keep this child I will mount your immortal head on one of those sharp pointy things outside my office as a reminder to everyone that even though I am the Healer I am not a pansy!"

Michael: Wait, it needs something. Wait, I know - ambiance!
Music: You're the best, around! Nothing's gonna ever keep you down!

His face looked like this: X_X