I did not kill Patriarch or Seth (except to test the 'reviving dead NPCs' procedure on Seth in a temporary save). I would have killed Seth for his sword, but was past that point before I found out about it; any future games I will be doing something different than a warrior using a sword, so he is safe from me.
I do kill bunnies and cows, though. <img src="/ubbthreads/images/graemlins/badsmile2.gif" alt="" />