It’s a natural thing for a creator to worry about the secondary characters stealing too much of the spotlight. It’s happened in fiction of all stripes, particularly when the main character is left fuzzy for audience insertion purposes; it’s a common risk in RPGs, and likely to end with a bunch of very annoyed players. You’d think the easy thing would be to hold back with a secondary character, to try to make sure she isn’t grabbing more of the limelight than she deserves, and if she grabs a little less—well, better that than a little more, right? And then you get a response like a conversation I had with one of my players the other day, where he pointed out that one of his two complaints with my game is that the NPCs weren’t being awesome enough overall and requested more like what had just happened in the last session. I have to admit, he was right.
So how does a secondary character end up “not awesome enough”?
She doesn’t live up to her own potential. Over the course of a plot, we see secondary characters doing things, and generally remember what they can do. This one’s never been anything but calm in a crisis, this one has a super-entrenched spy network, this one has trained for years in a couple of obscure but impressive martial arts, this one invents spells in her spare time, this one is particularly useful when the enemies are popping up en masse… you get the idea. But then the character gets into a situation where anyone who knows her would recognize that, from what they know about her, there’s something she should be doing right now. It’s not something that requires a twisty mind, or lateral thinking—it’s an obvious reaction. And for some unexplained reason she doesn’t do it—or worse, she actually claims she can’t do it but there isn’t a good reason why it’s different from That Other Time When She Did Something.
She doesn’t live up to her teammates. I’m not saying that secondary characters need to be equal to the mains, and I know as well as anyone that in a game situation, the NPCs all being better (or even equal but prone to better rolls) can be a source of frustration. But on the other hand, there’s got to be some reason why the main characters keep the secondaries around, particularly if what they do involves personal risk on a regular basis. If the secondaries are an active impediment to the primaries, and there isn’t something else they do that makes up for it, why are they there? (I will note now that I have a very broad definition of “something else”.)
She doesn’t live up to her environment. A lot of settings, cultures and organizations have expectations for their members—in the latter, failing expectations might just mean being kicked out, but in the former, not being up to par might be fatal. If a master diplomat is failing at politics and conspiracy detection, if for some reason a career military officer (in a military that doesn’t allow money or bloodlines to substitute for competence) is fainting at the sight of blood, if someone who’s been living out in the wilderness for five years gets woozy if she doesn’t get her breakfast or has to sleep at least ten hours a day on a proper mattress, people notice there’s a problem. Therefore, make sure you know what the minimum levels of competence are for the character’s circumstances, and make sure that if they aren’t meeting them the rest of the time, there’s an explanation for why they’re still apparently functional.
The main characters may carry the fascination factor of a story, but a lot of the times, the believability rests on the secondary characters. Make sure they’re as good as they’re supposed to be!