Here's something that's been stressed in my Form and Technique class: don't label characters.
It doesn't matter if you're writing them or reading them. My professor calls 'labeling' your character 'diagnosing' them, and frankly I agree that it's the same thing. And to illustrate what I want to say on this, I want to bring in Ronnie from THM:
She's a bionic super-soldier, amnesiac, violent. She can be characterized by sudden, angry outbursts in which she loses the ability to gauge her own strength. Heck, one of the things that I, personally, use to describe her is that she has heavy anger management issues.
That's where I want to stop: anger management issues.
It's a descriptor, sure. But there's a danger in using a term like that to describe a character, even if it's one of my own. What I have to remember-and you, too, whenever you're reading or writing-is that there's so much more to them. Just because there's one characteristic that seems to dominate doesn't mean that that's all they are. It makes the character flat.
It labels them.
As the story progresses, you should be able to see more. I hope that readers would eventually see Ronnie's fear; I want them to see that there's a reason why she holds back from people, and why she also cares about them so much that she's willing to destroy herself to protect them, that above all her loyalty is what shapes her. I want readers to be able to look behind her anger and realize that it's just an effect of something bigger.
She's not defined by it.
It's an issue of making sure your characters are well-rounded. When you first come up with them, there's probably only a handful of things you can define them by. I'm going to admit that when I first found Ronnie, all I saw in her was the violence, the anger, and a detached coldness that pervaded her. One of your jobs as an author is to look behind all of those initial impressions and figure out why, and use that to learn more about them.