When I started seriously writing fiction, at age 13 or so, I did what many books and blogs advocate today. I wrote what I knew. I read a lot of books and comics, and watched a lot of television and films. Because of this I knew strong hero types, so they were what I focused on. I bought a lot of role-playing games, but I moved around a lot so I couldn’t always interest others to play them with me. What did I do? I made a lot of characters and made up their adventure stories.
It didn’t take long for me to realize that powerful heroes work well for short time spans, or to interest young readers, but they grow boring when you deal with them more often, or for longer periods. Even at 13 and 14 I started adding psychological flaws to my characters. Even if I didn’t completely understand them at the time, I knew they made the character more real for me, and so I liked them, and their added depth, better.
I grew older and my interests changed, but I never grew past my love for flawed characters. I started role-playing in different settings and with different people, and I got involved with acting, and my writing only grew more detailed and character driven. Motivations became more and more important as well as dialogue, but I found more came from the cracks…from the character’s shortcomings, than from their strengths.
I started to realize that the weaknesses of my characters could really be used as the strength to drive my stories. I realize that most people reading this will, no doubt, know this already, but it came as quite the shock to me. I was even more shocked to find that it held true in every great book I read. Look at the books you've read and loved. What were the weaknesses of the lead characters? Would the story have been as good without them? (I doubt it.)
Every character I developed from then on, and it's still true of characters I create to this day, started out as a blank slate. I add their psychological background – from their nature and their nurture. From this I can draw a picture of their deepest personality strengths and weaknesses. This lets me really get to know them as people, at the core of who they are; no matter how alien that might be. Anything else they are, Vampire, Ghost, Zombie, Wizard, Witch, Corporate accountant, Politician, Lawyer, gets layered on after that (and is effected by it, accordingly).
I’ve talked to several younger writers who decide they want to tell a Vampire story or a Zombie story so they just make a ‘good guy’, or a ‘bad guy’, shake, and serve. They don’t understand why people tell them their characters seem shallow or two-dimensional. I’ve suggested to a few that perhaps they’d gain additional depth of character by adding faults and psychological roots, and that might aid their story. This has helped some, while others have just slapped a phobia, or a strange compulsive quirk to their leads to make them unique. A quirk like this, added just to be there, only makes your character different. Different doesn’t equal better.
I have a feeling I’m rambling here. What I’m trying to say is consider the negative in your positive characters. Hell, consider the positive in your negative characters. Above all, though, consider where the positives and the negatives in your character come from. What is the emotional, mental, and sociological genesis point of your character? Find their beginning and watch them grow before you write them into your world, and you’ll find they have so much more to contribute once they’re there.
That’s my two cents.