I spent a good portion of today working with some of my favorite secondary characters. Playing with them, seeing the subtle cues the left in the text, and wondering which ones readers will like the best is always fun. Surprisingly, I've had different betas pick just about all of them as their favorites, which is really encouraging.
So what's secret to good secondary characters? I mean, I'm flattered you're asking me, but there's better people to consult. Still, since you're here, I might as well give my two cents. And since The Paladin is loaded with secondary characters, I can give a few different thoughts about what I think and what I've done with all of them.
When I come up with secondary characters, really their personality is sort of dictated by the needs of the story, first, then fills out from there. I still do a lot of deductive character building when them, so when I figure out what role I need, I can use that to decipher what their personality might be like. If someone holds a high rank in an organized military-esque organization, it's unlikely they'd be juvenile or immature. If they are, there should be a good reason, like nepotism.
Making sure their personality fits the role they've been placed in is key to getting them started, but I think the next thing is creating something about them that's relatable. Something human. I'm sure you've heard it before, but even your villain needs something in them for your reader to grab onto. Evil for evil's sake is really hard to pull off. At the same time, you need to make sure that they're still in the wrong. If your reader decides the bad guy is right, that Thanos was right to kill all those people, then you risk losing their interest in your main character.
The last part I'll mention ties in with relatability, and that's the details. These are what really makes the characters pop and come to life. Their motivation. Their desires that aren't tied to some overarching plot arch. Does your character collect bells? You don't have to throw it in the reader's face, but if they happen to pass a bell, make sure they take time to admire it. Or steal it, I don't know. Point is, these people need to have lives outside what the reader sees. Even if you never directly reference them, knowing their interests and hobbies helps flesh them out in your head so you can flesh them out on the page.
So there's my thoughts. What about you guys? What secondary characters do you really like and why did they stand out so much to you?
Keep your eyes open for my debut novel, The Paladin.