Creating characters can be daunting. There are simply so many personality traits to juggle. Once having drafted a synopsis the time comes to hold auditions. Pick the wrong traits and the character could very well take over. Brevet General George Custer’s scout, Half Yellow Face of the Crow Nation, warned him about the encampment at Little Big Horn. Custer was hell-bent on attacking and ignored the information. Half Yellow Face responded, “You and I are going home today by a road we do not know” As the knight in Indian Jones and the Holy Grail said, “You must choose, but choose wisely.”
But
. . . but . . . how?
There are lists galore of personality traits. Something I stumbled on involved horoscopes. Whether you are into that sort of thing or not, over the years (centuries ?) compilers have categorized twelve types. Each attributes strengths and weakness along with likes, dislikes, and compatibility with the other eleven. What we have is a thesaurus of personalities.
From the synopsis, you have a general idea of what they should act like to give the desired outcome. By picking one of these types that comes close, the next step is to select a few appropriate traits from the list that will promote or distract from a solution of the plot. As a bonus, take a look at their likes and dislikes and what personality they would get along with and who they won’t.
The attachments are a compilation of a number of websites that have drawn from other sources who have drawn from . . . ad infinitum. Not included here due to space are also some good narratives on the Internet about each type. Might be worth looking at.