I understand what you mean but thats kind of a problem tied to 'the player controls the npc's and gets to pick what they say'. That said, rben the evilst of characters will know that it usefull to appear to be nice. He might not believe what he says or does believe it, but with a caveat attached that he isent adding.
In your example Astrion saying that he loaths human but loves to suck them dry of blood would get....mixed results in that case. While appearing to care about a life would not.
That's very true, it could all be an act. I hadn't thought of that before.
