Evil is a trait in The Sims Medieval. It conflicts with the Good trait. This trait seems to have much in common with Evil trait in The Sims 3, even so much as having the same "Fiendishly Delighted" moodlet/buff.
Evil Sims take great delight in the misfortune of others, and prefer to lead a life as far away from goodness as possible.
- Your Sim will get a Fiendishly Delighted buff when misfortune strikes nearby Sims.