Characters need to be relatable and human in order for a reader to continue to care about the story. Building a character can thus be a complex process because more often than not, the writer either puts too much of himself/herself in the character or creates one that is a secret fantasy of what the writer wishes to be.
For example, I may create a character with zero inhibitions and overly adventurous. If I start writing a story with such a character without doing proper research, I would eventually come to a block which I won't be able to overcome. If I want to create a 'human' character, just giving it my opposite personality isn't going to work.
I read somewhere once that before writing a story, the writer should take an imaginary interview of the character and note down likes and dislikes to form a personality for him or her.
I did try doing that, but this device never worked for me. I would start writing a story that takes place in a desert, for example, check my "interview" notes and find that one of my characters hates the rain.
Umm….no chance of rain falling in the desert. Eventually I would get confused on how to proceed and whether to pick the story I had carefully planned or the character.
This may seem like a trivial issue, but to a writer, changing any aspect of a story is a hassle because it interferes with the primary vision I had for the story. I could let the character like the rain and therefore have him wish that the sky would burst open and let cool droplets fall on the parched travelers, but that would mean I would have to change the character's back story too.
He hated the rain because the floods in his village had claimed the lives of his family. He was aggrieved and had suffered a great loss.
You are but a product of your past.
Now that I had changed one trait, the character no longer made sense to me and the vision for future sub- plots in the story were disrupted because of this one tiny change. The character and the travelers were going to befriend a camel in the desert and he would learn that he would have to keep living his life after seeing the resilience of this one camel.
Then I thought that I could perhaps change the backdrop of the story and make it into a rainforest. The character could still hate rain and he would have some interesting snarky dialogues to make. But nope, that wouldn't work because of the camel sub-plot. No camels in the rainforest!
See the dilemma? There may have been a third way out, but I just couldn't see it. My vision for this story was destroyed and the story was ultimately scrapped.
What I do now, is to create a back story for the character and live the world through that character's eyes. I make up a situation and wonder how that person would look at this and respond to it. What perspective would she have gained after her past experiences that made her who she is today?
I guess I'm one of those people who write better when they visualize.