Mettaton doesn't respond for what seems like an eternity, but what probably only lasted five seconds. Five very long seconds in which he was practically lost in himself, not sure whether to argue or to agree, because the fact of the matter was that it all hurt.

Every single derogatory statement Chara had used against him bit into him like the sharp tip of a knife piercing through his very SOUL.

Mettaton looks up and there's something unspeakable in his eye, like he's really just considering whether he wants to slap that smug little smile off of Chara's face, rip it off slowly and watch them bleed out, or just...break down right there.

Instead, he closes his eye and speaks quietly.

"You have made your point. I'll take my leave."

They're right, they are. He's an awful, terrible monster and he cannot ever resolve that in himself. At least they'd reminded him.

Mettaton turns his back on Chara. It's almost an invitation--but it isn't as if he care about being vulnerable. He's been vulnerable for months, and this is what he had wanted anyway. Someone to agree with him, that he is a bad person.

I don't deserve sympathy. I don't deserve to have a family here. I couldn't even be a good cousin to my real family.

He begins to walk away, repeating those thoughts to himself.

Chara had won. They didn't even need a weapon after all.