We’re having a sale. Today only. Buy one protagonist, and get the antagonist at a fifty-percent discount. Such a deal. You can’t have one without the other.
I teach writing to sixth grade students. Here’s a typical plot line: Character meets another character and they talk. Then they meet a third character. They talk some more. Finally they all rush back to a) home, b) school, c) a castle. Yes, I know it matches up with a few of the Twilight books (don’t be a hater, I actually like Stephanie Meyers), but what most of my tween writers lack is an antagonist.
Or to be more specific, conflict generated by an antagonist. The two are inseparable. Yes I know that the protagonist herself can have doubts, thus generating conflict. Likewise, nature can also be an obstacle. But let’s face it, nothing beats a good ole white hat versus black hat. (If you wanted to go the Twilight route, Meyers handled that quite well.)
The antagonist defines the protagonist. He often strives for the exact same goal as the protagonist. Since only one can achieve that goal, it creates tension. I love antagonists that mirror the protagonist. For example, if I have a protagonist who hates monsters and the grotesque, I might pair him with a an antagonist who is a monster herself, yet despises it. Perhaps they’re both seeking the goal of destroying the evil beasts. Yet our hero does this out of fear and ignorance, while the villain strives for this goal from self loathing.
However you achieve it, make your antagonist linked to your protagonist. It creates a deeper bond and makes the final mano-a-mano showdown that much more interesting.