I would argue that every protagonist in fiction needs a major character flaw. Part of the satisfaction of reading comes from finding out how a character changes for the better.
Of course some character flaws are greater than others, and when you make your protagonist seriously flawed (as I like to do), the question becomes: How do I keep the reader invested in the story? How do I keep the reader from wanting to throw the book across the room?
The answer is: I don’t. In my first novel, A WORK OF ART, my main character, Tera, refuses to believe that her father is guilty of a crime. Her naivety evokes a certain reaction in the reader. I myself wanted to grab Tera by the shoulders and yell, “Wake up!” And yet (if reviews of my book are any indication), most readers stayed deeply invested. They wanted to know what happened to Tera. They wanted things to work out for her. So how did I accomplish this?
I discovered that one way to make readers care about your character is to bring out the character’s vulnerabilities. Tera is a loner at school—to the point where she eats her lunch in the girls’ restroom rather than sit in the cafeteria alone. Also, her home life isn’t that great. Her father is dominating, and her mother is manic-depressive. Through flashbacks, the reader gets an in-depth look at how Tera has always had to struggle to get her father’s approval.
So Tera’s character flaws make sense to the reader, and that, I think, is why the reader continues to care about her even when they see her making poor decisions.
In the novel I’m working on now, I also need to make sure the reader stays invested in my main character, despite her poor decisions. Layla is a teenage girl who’s been living in a homeless shelter, but suddenly she gets to move in with her rich aunt and uncle. Sadly, she lets all that good fortune turn her into something of a snob, and other characters in the story get hurt. My job as a writer is to make sure the reader doesn’t end up hating Layla for her poor decisions.
I’m doing that by showing Layla’s vulnerabilities. Layla is constantly struggling to keep what she has. Her father died before she was born, and her mother is an addict who can’t seem to stay clean. Because Layla has never had true stability in her life, the reader can understand and even forgive the decisions she makes. In the end, Layla learns a valuable lesson, and that, in essence, is the whole point of storytelling—to show how characters overcome their own flaws (along with all the other obstacles in their path) so they can triumph in the end.