"They look like monsters to you?"

[question?]

By saying they aren't monsters doesn't mean they appear as human to him, it just means that perhaps beyond the hideous exterior they are inwardly un-monstrous.

I thought of that, but they act monstrous, meaning they attack and kill without provocation. Of course, that could simply be a part of Heather's perception/dillusion/whatever. Or were you simply saying that Vincent sees beyond even their actions, recognizing the humanity that once was?

On the other hand, if that's the case, Vincent shouldn't be surprised that Heather doesn't see beyond their "surface" appearance.