The writer must think of the character as a whole. Characters have habits. Characters have a past. Characters are complex.
A character may have faults, and on the other hand, they may have gifts. A character may be deranged. What made him/her deranged? Born that way? Or the derangement may be a temporary thing, the result of a situation or a reaction to some outside stimulus. A character may be kind, generous, and given to putting money in every homeless person’s hand. Why? What made that character so kind? Or is this character putting on an act? Or is this character tired of the rat race and planning to give away all their earthly goods in order to exit the world with no baggage?
Each character presents so many choices to the writer. And a good writer will make concrete choices about each character in their work in progress.
In writing characters, the author should go back to the character’s beginning, and answer question as to why the character become what they have become, good or bad.
I found this excellent post by Roz Morris about writing characters with addictions. We all have addictions of one kind or another – from heroin to chocolate. She points out the questions to ask yourself. I thought it was a great article. I hope you enjoy it also.