Once upon a time, there was a very large dog who was absolutely certain of his job in the world: making sure Big Blue Intruder did not break into the house. He protected the house every day, rain or shine, by barking furious threats at Big Blue and when Blue had been chased back into his van and driven off cowering in fear, Dog peed on the fence posts around the yard to make sure everyone knew this was HIS yard, and woe unto him who tried to enter.
As you might imagine, Fence Post didn't see things quite the same way Dog did. Fence Post knew his job was to keep Dog IN so that the postman didn't smack him on the nose and pepper spray him. Fence Post was pretty good at his job but the peeing was really getting annoying. And kind of wearing him down frankly.
So one day, when Mr. F Post had had just quite enough of Dog P, he tilted. Just enough to let Dog out, and right when the Big Blue Intruder arrived.
Sure enough Dog got a snoot full of pepper spray, a not soon to be forgotten smack on the snout, and Fence Post got a good laugh.
To this day, Dog has no idea quite what happened. And no idea why. And hasn't even thought to ask Fence Post. Dog is kind of a doofus, I'm sorry to say.
The reason I mention this is because where you are in the story, post or pooch, makes a difference in who the good guy is. And yet, as a reader, it's so very satisfying when you can see the world view of both the good guy and bad guy. Thus: the antagonist is the hero of his own story, much like Dog is the hero of his.
When I get queries for stories with one or two dimensional characters, particularly the villain, I lose interest.
How do you convey three dimensions? Words of course. What's said, what's not said.
And honestly, you're the writer here. You probably can figure out a dozen ways.