- Evil for evil's sake. This antagonist has no real reason to be evil/do evil, they just do it because they can.
- Evil because it can grant immortality. This antagonist has latched onto an idea that promises immortality, yet to do so, they have to perform some sort of horrific act that any sane thinking person would not do.
- Evil by nature/nurture. This antagonist was "born into" whatever position that they are in, be it a psychotic serial murderer, or dictator that is to "carry on the tradition of their lineage".
Bleh. Drivel. Some of it can be entertaining drivel (Harry Potter is a current example of this), but really, it's at best brain candy, as opposed to good stories.
Let's put aside the evil versus good discussion for a moment and discuss psychology for a moment.
Most antagonists are human, or (as in most fantasy settings) have similar mores to humans concerning the basic principals of life and the treatment of others. Most people have some sort of internal moral compass. Some may not match our own, but they have a set of morals that guide their decisions. Most people would rather be left alone to their own devices. "You let me play here, I'll let you play there, we'll be kosher." There are outliers, power grabbers, those that wish to be benevolent dictators, but honestly, most of us want to do our own thing, and not be bothered too much.
Now, before we continue with the idea of believable antagonists, let's look at what makes a great, believable protagonist.
Most good fiction is written in such a manner that the reader tries to put themselves in the shoes of the protagonist. We live these characters lives with them. We hurt when they hurt. We celebrate internally their victories. Good protagonists we can empathize with. They breathe. They live in our minds. The best protagonists will move our emotions and lives in such a manner that it gives us pause as we reflect on our own lives and wonder how better to emulate the good qualities of the protagonist.
One of the most common definitions of "hero" is "a man distinguished by exceptional courage and nobility and strength". I refine this further by saying that a hero is "a normal person performing extraordinary feats in extraordinary circumstances".
A good hero we can click with. We *want* them to win. We *want* Joe Sixpack to become an avenger and kick the crap out of people who deserve it. We *want* to be that person, because, from our perspective, they *are* the everyman, living with unspeakable demons in their lives, and dealing with them in a manner that idealizes the human spirit of tenacity and justice.
So, with the above in mind, let me break down what to me makes a believable antagonist:
- They are the same kind of person that the hero is. The best antagonists are cut from a similar mold that the protagonist is. The closer the better. It lets us know that there *is* a darker path that the protagonist could have walked, but chose not to because of decisions made, and events witnessed.
- They have a noble goal. The thing they fight the protagonist for is admirable. They desire good ends to their actions. They believe, and can make you believe that their goal is just.
- They, like the protagonist, believe they are on the right path to reaching their goal. They have considered options, weighed consequences, and struggled with the decision that they have come to. They walk the path they do, not because it is right, they walk the path because it is the only way they see they can attain their goal.
Get close on the three above, and you'll have a readable antagonist that is a worthy adversary to your everyman hero.
An example of a *great* antagonist, from the most unlikely of places, Hollywood: Magneto from "X-men, the movie".
Magento and his adversary Doctor Xavier are very similar: Both (while extraordinary) are cut from similar molds as people who have extraordinary abilities. They both have the same goal of integrating these extraordinary people that have started evolving from humanity into the rest of humanity in a manner that they can coexist peacefully.
Magneto, however, has come to the conclusion that humanity will not accept this new stratification, these superior beings, peacefully, if at all. The rest of humanity will only accept this if the leaders of the world deem it necessary for them to do so. His plan is to forcibly cause this transformation in the leaders of the world. Even if it may cause the death of some or all of these leaders.
That, my friends, is an *excellent* protagonist, and the story told is wonderful.