User blog comment:FairyRaven/Fairy Tail Chapter 406: The Girl Within the Crystal, Review and Commentary/@comment-25572451-20141027233911/@comment-7418318-20141028091431

I could imagine Kain not really being evil. He's ... simpleminded enough that his evil tendencies might have come from following Hades around for too long, but Rustyrose is a different matter to me.

He seemed to enjoy tormenting others a bit too much and was not just willing but practically joyful about sacrificing 90% of mankind for the Great Magic World.