No matter what you call them–antagonists, bad guys, villains, opponents–they always get a bad rap like 7th grade bullies.
It only seems natural that we think of antagonists as evil because they make it increasingly difficult for our main characters to reach their goals. And because we love our main characters and want to protect them and watch them succeed, we make sure we create antagonists our readers will hate.
But antagonists don’t have to be evil, and we shouldn’t always think of them so one-dimensionally.
Regardless of whether it is your protagonist or antagonist, all characters are motivated by something. All characters have a distinct and specific internal need that drives them, however subconsciously, toward their goals.
Antagonists are no different, though usually they are motivated by ignoble desires like greed, lust, power, and revenge. But if we truly look at what causes those characters to embrace their dark side, we’ll see some sort of tragic event in their backstory. Perhaps they were subjected to neglect or abuse, witnessed corruption or violence, were bullied or humiliated. Enslaved even.
These are all events that could have happened to our main characters too. And in either case the internal need for each type of character is the same: the need to be protected or to protect, the need to be loved or to love, to be accepted, to be recognized, to face fear, to just be happy.
Unfortunately, while our protagonists take a more worthy approach to fulfilling these needs (saving the world, kittens, old people), our antagonists take a slightly different, selfish path to reach them.
So when dreaming up your antagonist, try to sketch him as a complex, multi-layered character and not just a vehicle to make your protagonist’s life hell. Ask yourself what he is motivated by and what need he is trying to fulfill. For instance, a teenager living in the ghetto whose father always told him he’d amount to nothing may choose to join a gang and prove he is worthy of his father’s respect. Not evil (though he may do evil things), just a bad choice in how he goes about proving it. Another kid with the same history may choose to further his education, become a lawyer (much more evil), and move away. The same need, a different, more moral (cough) response.
Which brings me to another bit of advice. There are two different reasons your antagonist and protagonist will clash.
First, your antagonist may want the exact same goal as your main character. For instance, two men fighting over the same girl (if only).
Obviously, they will both do things to stop the other from getting her. Your protagonist will choose more righteous actions while your antagonist will generally be a douchebag. Is the latter evil though? He may be, but he may also be your main character’s best friend. What makes it wrong for one man to fall in love with that girl and not wrong for the other? Both inherently need to feel loved, though one may be motivated by feelings of inadequacy, low self-esteem, or jealousy.
Secondly, your antagonist and protagonist’s goals may be mutually exclusive. That is, one may not want the other to reach it. For instance, the Nazis wanted the Ark of the Covenant for power. Indy didn’t want them to get it.
Did either achieve their goal? Technically, yes, but not in the way they had imagined. And that’s okay if the goal doesn’t turn out the way your characters think or want, if the ark ends up in some military warehouse where another power-hungry leader can get to it. At least your main character saved the day for now. Not for reasons of power or greed or lust. For humanity.
And that, my friends, is my humble opinion on the difference between protagonists and antagonists. It’s not that their needs or goals are necessarily different; it’s that the antagonist, growing up jaded and cynical, is motivated by selfish reasons and makes bad choices.