Using anger in fiction is a seriously great way to engage the reader and to help progress the story-line as long as you do it right. You can’t just write a passage where the characters seem to be angry and hope that you have conveyed the emotion, you have to feel the anger to be able to do so. Cast your mind back to a time when you felt sheer rage, so much so that you felt the pressure was a tangible part of your being and you thought you might explode if you didn’t get that angst out. This is exactly how you need to feel to be able to write it. I am not suggesting that you wait until your next bout of anger, but you can recall the memories easily enough and it’s that experience that you are after. Try it and see. You’ll have your story and characters come to life far more quickly.