That's a very interesting way of looking at this. I've always struggled with finding a character's flaw; perhaps this approach will help. Thanks!
I never really thought of it but now I have noticed all my characters have flaws not one of them is perfect and my main character is definitely not perfect, in fact his imperfections make him able to perform some accidentle saves as a hero! I love things like that, you think the character isn't going make it cause they don't have the skills but they end up fluking a move or something!
I think 'perfect' is subjective.. Do you mean your character is 'good' and doesn't do anything we could perceive as wrong or evil? Do they make all the right decisions or always defeat their enemies? That sounds like a pretty boring story, but it fully depends on your plot and what you're trying to accomplish with it. Most of the time for a plot to progress, the character/s should learn/grow/change in some way. For your characters to do this there must be a reason/plot device for them to do so. So adding a flaw from nothing would obviously not work and not make much sense.
I would recommend you go to the TV Tropes website and look at the various character archetypes that are listed there. For each important character in your story, pick an archetype. Then, for each character, come up with three to five traits that describe that archetype. For example, one of the archetypes is "Little Miss Bad-ass". Some traits that might characterize that archetype are: "Adorable", "Playful", "Giggly", and "Deadly". Every single time your character appears in a scene, have the character perform whatever actions need to be taken to push the plot forward. But, have those actions be performed in a way that epitomizes one of the character's traits. While doing this, however, never specifically use the words of the trait in your description. Rather, have your words dance around the trait without stating it directly. So, while describing your "Little Miss Bad-ass" approaching a villain, dress her in a bunny costume and have her skip her way toward him with a beaming smile before she plunges a crayon up his nose and into his brain. Pick your character traits and push them for all they are worth without worrying about whether they are strengths or weaknesses. Just about any trait can be either in the right circumstances.
