I was reading a book recently and the author did something that really bothered me. She gave the heroine a huge, enormous issue in her backstory, but then largely neglected it except for lip service now and then. I guess you'd call it a wallpaper character issue.
If, as a writer, you choose to give a character a life-altering event in their past, one that is supposed to have affected them for a long period of time. One you tell me that they still haven't healed from. Then it requires that the issue be dealt with over the course of the book. Don't tell me they feel a certain way and then have the character immediately act as if the issue never happened. Not unless your character is also dealing with denial, but that wasn't the case in this story.
So here's my take on things. First of all, while a writer needs to know a ton of stuff about her characters, the reader doesn't necessarily need the information if it has no bearing on the story. Secondly, if you give your heroine (or hero) a big issue, it has to be dealt with during the story and it can't only be mentioned on rare occasion. Third, the character's change is called a growth arc because it happens slowly. People do not get over traumatic events as easily as flipping a switch.
When I wrote Through a Crimson Veil, Conor had one of these enormous issues. He was conceived when his mother was raped by a demon. Because of this, he hates demons...and he hates the part of himself that's demon. His heroine is also half demon and her presence--and how he reacts to her--cause him to have to confront his issue. Believe me, normal people (and our characters are largely normal even if they're demons or mercenaries or whatever) don't want to deal with their issues. They have to be forced.
So over the book, Conor learns to deal with being demon. But this issue is more than that. He's carried this hate his entire life. It is totally going to affect his interaction with the world. It will impact the way he thinks. It will impact what his choice of action will be. In other words, even when the issue is not directly being raised, it is still coloring every scene in the book. That's what major character issues do.
If, as a writer, you don't want to deal with that kind of thread, then I'd recommend giving the character a smaller issue. Small issues can cause tension and conflict, but are unlikely to color every scene or a character's every action.
An example of a small issue is In the Darkest Night where Farran had a scar. The scar was something that she only had for 5 months before Kel healed it and made it disappear. She didn't think of it all the time or touch her face constantly. But from time to time, she did remember it and it did affect her. The book itself, centered more on Kel's issue which was another enormous one--Post Traumatic Stress Disorder (PTSD). That did color every scene he was in during the book, but Farran's scar didn't.
For me, it's all about staying true to character and raising a big issue and then only using it when an author feels like (or remembers it) doesn't play. Real people, real life just doesn't work that way.
