Demons are, in general, pretty terrifying things. Crowley, being a bit on the softer side, hasn't been terrifying in a very long time. But Hastur, Ligur, all of them, very terrifying. And Aziraphale, right now, is completely terrifying. His head spins around, feathers sprouting out of his face, and it's absolutely everything in Crowley not to shove him away in complete fear.

Falling is a horrible, horrific experience. And if Aziraphale has Fallen, then Crowley has to pull through his terror and be there for his friend, he has to.

"You Fell----Aziraphale----you Fell and----"

Did Aziraphale die? Did Aziraphale Fall? Crowley can't pull himself together enough to work it out.