The idea above is really good, I hate enemies that are bad just because they're bad, also it may bring investigation, you could mass a force to assault him/her or hear some rumors and discover that if you save him/her from the raiders you're gatting a strong friend.
Althouhg that would not be an evil mastermind, most times they do what they do because they want things and belive they're more than humans so they're above the laws of Earth and mankind, and can kill and steal rightly. Or they are in deed some kind of god or superhuman entity, but that doesn't matter, they will pay.