[It's probably more of a loaded question than they think. But Rey just focuses on the more important subject, her gaze not wavering from the water below.]

You do realize that you're not the only killer in this city, don't you? That you aren't the only one who's done terrible things?

[And they aren't the only one who has ever considered, or acted out on, the things that Frisk has thought about.

[And then, she mutters:] This whole situation we're in was built on the foundation of bringing in awful people.