Mettaton opens his mouth to say something, stops, then closes it again. They sound... a lot like his mirror, only more nasty and mocking. Though the mocking isn't too far off either. Or the nastiness.

He frowns.

"Both you and your Alphys have said things like this to me and frankly? It's unneeded. I know what I am doing. I'd step away if this was harming me."

He sounds only a smidgen uncertain, even as he thinks of how he really can't say no to speaking to his mirror without feeling terrible on some level. But that's him. That's not his mirror influencing that. ...Right?