He tsks softly; he's not sure he likes the business of shackling people's souls (though he counts Undyne no less a person--and, he's obliged to admit, he captures goblin and ogre souls for his own use without pangs, so he is in little position to lob criticism), but he certainly doesn't approve of wholesale murder, either. "I am sorry," he offers. "Perhaps, if you have found your way here, you might guide your people here in turn, and so escape the humans' prison and predations."