Hey, look, just because you're super strong and metal on the outside doesn't mean you're not vulnerable on the inside. You probably have, I don't know, wires and such you need to operate. You can't tell me you're invincible inside and out.

[He scratches the back of his neck with a sigh, looking slightly sheepish. He wants to help Mettaton, protect him, because protecting people is all he really is good for, really.]

Whatever. You can take care of yourself. You've made that much clear.