[At first the robot thinks that perhaps that was enough. Perhaps Zacharie’s mirror was satisfied with his answer, and that their conversation is over. But then he sees writing return and- …wow.

Wow, did this guy seriously bring red paint for this? Did he prepare for this level of spooky? While, yes, on one hand Mettaton is a… tad disturbed by this development, he also feels vague amusement. Zacharie’s mirror seems to have a small flair for dramatics just like him. (Though small is not the word I would use to describe Mettaton’s ways.)

Past that, however, it takes him in kind a few moments to respond. He reads over the words on his mirror and is honestly…puzzled.]

No Mercy? None at all? Your Puppeteer has no choice?

[How? How is that possible? He doesn’t understand.]

How can there be no other outcomes? How can it be set in stone like that, how can…

[His eyes grow wide in horror as he thinks of how it could have been with him. How there could have been a world where no matter the circumstances, no matter the intent of The Player and Frisk’s SOUL, he would have died. He would never have gotten to the Surface, would never have seen his dreams come to life, or the dreams of everyone around him…

He sits back from the mirror.]

You mean to tell me that if my game were like yours, Frisk would always kill us? That even if they wanted to do something different, there would only be that end? That instead of only a few of us here who remember a time like that, it would be all of us?

[He’s schooling the panic out of his voice pretty successfully, except for the slightest hiccup towards the end of his sentence.]