Melanie's frown twists into a grimace. She didn't rescue him from anything, and if he's telling her the truth, she couldn't rescue him even if that man (for lack of a better word) was actually here and hurting Aziraphale in reality. Which wouldn't stop her trying, and she feels an uncomfortable surge of resentment as the truth of the situation sinks in. There's someone here who has hurt Aziraphale, and might very well try to hurt him again (what's stopping him?), and there's nothing anyone can do. She's just supposed to accept it.

She's accepted worse. But this isn't fair. She made things work for Miss Justineau; why can't things be made to work for Aziraphale?

"How do you know he's not going to do it again?" she asks. "What's stopping him?"