I'm not a big fan of the Schwarzenegger Conan the Barbarian, but there's a scene that sticks with me, even though I haven't seen it in over twenty years. At one point, Conan is talking to James Earl Jones, who leads the cult of evil snake-hippies (or whatever was going on in that movie-- have I mentioned it's been twenty years?), and Conan is espousing his belief in the strength and power of muscle and sword. James Earl Jones scoffs at this, and demonstrates real power. With a simple, kindly spoken call ("Come here, child."), one of the snake-hippie cultists on a high balcony takes a step closer to him... and happily plummets to her death.
I bring this up because very few fantasy villains ever seem to truly deserve the to-the-death loyalty they often receive. James Earl Jones in Conan is literally the leader of a cult, so it works. Plus, he's James Earl Jones, so he's got that voice and charm. It's easy to buy. But other times, I really wonder.
Take, for example, the Grolims in David Eddings's The Belgariad. They worship Torak, the evil god. Now, at least in the world's beginnings, Torak (and the other gods) had a direct, physical presence, which can go pretty far in inspiring loyalty. He's an actual god, and he's standing right there telling people what he wants them to do. But in the time the series takes place, Torak has been asleep for centuries, presumed dead. But the Grolims still act with fanatical loyalty. More importantly, they have fanatical loyalty to the two heads of the Grolim Church: Ctuchik and Urvon. (Zedar, in theory, is also one of the heads, but he doesn't seem to actively wield any political power, mostly due to disinterest.) But how do Ctuchik and Urvon inspire such loyalty? It's unclear. Urvon, in particular, is depicted as a sequestered, babbling moron who couldn't inspire fish to swim, let alone get a cult of unswerving loyalty to kill and die at his command.
This is what I want in my villains, at least those that aren't lone psychopaths: some sense that they inspire people. Even if those people are woefully ignorant and misguided. But if your underlings going to have the kind of loyalty that transcends just-earning-a-paycheck, I need to understand why they have that unswerving faith.