I want to expand the role of a minor character. I want to make him a villain.
How do I make him more real?
Lots of ways to approach this.
First off, you get to use all the tricks you used in building your major characters
on the small fry.
Give him something to believe in; give him a problem to solve; give him an interesting and complicated past; give him something that makes him hurt; something that he delights in, give him something he wants very very much, give him some small oddities of appearance, action, movement or belief.
That's pretty basic character building.
Here's four more approaches that might be useful:
-- What does he sound like in dialog?
Consider cadence of speech. Word choice. Accent. Big words or small ones. Modern slang or precise, scholarly finicky. Long sentences or short. Concrete terms or figurative. Metaphoric language or literal.
But it's not just the words. It's the delivery. It's how he speaks. What are the customs of his dialog.
Does he rush to agree with what other folks say? Does he interrupt? Does he respond to what has been said or go off on a tangent? Does he wait before replying, or jump into speech immediatly. Does he stay silent and carefully watch others?
Compare the dialog and delivery of Uriah Heep with that of Bill Sykes. Look at the accompanying body language. (Go ahead. I'll wait . . . )
And moving right along.
-- What does your character do? Nothing defines a character like what he does.
A small behavior;
(he hides his meat under a pile of rice at the cafeteria line so he doesn't have to pay for it;)
reveals larger behaviors;
(he's an embezzler.)
The lovely young girl who casually stomps on a cricket, ('insects give me the creeps',) is not lovely inside.
What folks do stands up and shouts so loud about what they are, that we can't even hear them explain that they are not really like that but are something else altogether.
-- Minor characters, maybe especially villains, tend to have simple and consistent behavior.
But while the balance and pace of the story may demand this simplicity of character, it's worth remembering that no one is all of a piece. We may not show the many depths to this villain bloke, but those many layers exist. We know this, even if the reader doesn't.
-- And it's often useful to remember that every character is the hero of his own story. How would he see things?
For some interesting comments on hero-age and villain-age, see the Wenchposting here.