[Asriel's still reeling, enough that he barely notices that Mettaton is seeing someone else. He rubs at his eyes quickly, giving a quick glance at his hands to see if they were bloody - they weren't, thankfully. His disk isn't out, isn't covered in blood, and Mettaton isn't...]

I-I... it's nothing.

[Mettaton wouldn't want to hear that he looked like his dead owner for a few seconds.]

We... just have to remember that we're both real. This place is tricking us with illusions. We can't...

[Mettaton's form shifts for a second - into an image of Toriel. It takes all of Asriel's effort not to lose his composure.]

It's trying to get into our heads.