It's a little odd, really, listening in on Frisk's thought processes. They had some insights very early on in their journey through the underground, but Frisk went away so early...

"I can honestly say. Unless "the stuff" is immediately relevant, I won't intentionally rub it in Dr. Alphys's face. Presuming she even shows up," Chara says. "And if that isn't good enough for you, then. Shut up. And stop being cryptic."

They're the only one who's supposed to be cryptic around here.