A good example of this includes moonstones. Moonstones often become more beautiful because of their flaws, as seen in this picture. Its the intrusions, the cracks, and the flaws that give these stones their fire. Without them, they wouldn't be quite so beautiful to me.
To the average person, they're of little value. They aren't perfect. To me, they're beautiful because of the flaws, not in spite of them.
Flaws are found in nature. Flawless stones are so valuable because they are so rare. Perfection doesn't happen in nature often.
Why should it happen in your books? Your characters are natural beings. By this definition, they are not perfect. Your characters should be as full of flaws as these gemstones. In the case of the moonstone, the flaws are what bring out the brilliant blues and yellows when held in the light. In the case of the spinel, it is what makes it glitter like a ruby, bringing out the vibrant bursts of crimson among the purple-red quality of the stone. The oval-cut quartz, intruded by veins of tourmaline, is a dark knight of the gemstone world; beautiful in its own way, but treasured by few.
The flaws in your characters are what make them beautiful. A perfect character is boring. A perfect character won't glitter when it catches the light. They're flat and they're dull. There are no dark lines to give a plain, clear stone character. There are no blues and yellows to draw the eye and capture the imagination.
Consider the flaws of your characters carefully when you create them. Those flaws are what will draw your reader to them and make them all the more real.
Reality is full of darkness, of color, of light reflecting off of cracks, which in turn makes something beautiful out of something ordinary.
Flaw is not a word for ugly.
I started the grunt work on a novel today. It's a standalone. When I created the lead character, I started with her name, her age, her hair and eye color, and her general body build. Then I wrote the following, spaced out by about 6 lines:
A character's personality is determined by their past and their present, and changes based on the things they want for their future. By that, I mean their goals, motivations, likes, and dislikes.
The first thing I wrote about this character?
She is afraid of horses and has a limp.
These are flaws. Her limp is because of an accident involving horses. That's why she's afraid of them. Her limp is a physical flaw. But, I took it a step further. How does this physical flaw hamper her? She's not of noble birth, but rather a merchant family striving for bought-nobility status.
Limping, therefor, is a problem. One that she trains herself to ignore — so, she walks ‘properly', ignoring the pain this causes, unless she is very relaxed or it is so cold out that she can't ignore the pain and limps despite her best efforts.
That is when the first personality trait came out. A character with this trait must be stubborn. Only a stubborn person could withstand such pain.
That led to the next trait: Selfless.
Someone who didn't care significantly for her family or for her role wouldn't do it. It isn't a selfish act, it is a selfless one.
She loves to dance, but can't dance, because she can't handle the movements without limping. This is a little bit of complexity added by her problem. She can't run, but that's fine — a lady shouldn't run.
Even if she'd like to.
Maybe she wishes she could use a sword, but can't because the footwork involved in swordplay is something she can't do — not without limping.
This is a character founded on a simple little flaw. A flaw, that like the stones above, is something out of her control, yet it is something that has impacted her entire life.
She has personality flaws as well, but I won't go into those here — what I've presented is enough, I think, to demonstrate the point of this post.
Flawed characters are rich characters. Pick a flaw — any flaw. Make the character greedy. Make them self-conscious. Make them so self-conscious that it is a flaw. Ask yourself this question: How does this flaw impact my character's personality?
Your character is an onion, made of so many layers that you can't peel them all away with ease. By the time you find the heart of them, you should have teary eyes and the nature of that character should be exposed, just like a flower in bloom.
Characters should be complex. That said, complex characters need not be hard to write.
Just be aware of their flaws, and remind yourself that they exist. Their flaws will speak of their complexity without you ever having to do more than show their lives through their actions.