Having written fourteen novels, seven of which are on Amazon, here’s my take on characters. If a character has a trait; a limp, a lisp, a verbal tick or that character is a race different from other characters, it needs to be for a reason. Either it’s for differentiating the character from others or it is integral to the plot. Having a black character in medieval England without explanation will be jarring and off-putting to the reader. The reader will keep expecting that trait to be important at some point. Another problem is characters are caricatures. Only the main character can be fully fleshed-out. So, you’re going to have a black person in a role originally written for a different race you’ll either have to imbue him with what people consider black traits, or you’ll be constantly pointing out that he’s black even though he doesn’t “sound” black or “act” black. An agent told me about a novel I had submitted if I made the main characters gay, he’d represent it. I reread the whole thing wondering how to handle the change and nothing in the plot worked the same way. Plotting a novel or movie is like building anything else.
You design to accomplish a particular task. You wouldn’t, for example, install a lounge chair in a race car. (This was when I decided to go back to engineering.)
“Plotting a novel or movie is like building anything else.“
Damn right. Change a line on page 38 and totally screw up something on page 92!