[It's sickening. It's sickening because it makes sense, and because every single mirror here is safely beyond their grasp. They can do nothing about this crime. The guilty ones will smile smugly and go about their lives unfettered.]

Why would Frisk ever trust a mirror? After what their own mirror did to them, why...

[Their stomach twists just thinking of it. Broken fingers and hateful words. Things that had belonged on the Surface, things that never should have had to hunt them down here, too. How could Frisk put themselves completely in the hands of one of those creatures after finding out that was how they were willing to act?]

How could they possibly shun us and embrace one of them?