nice character, rough sketches

You don’t really need to tell them what to do, or how to function, as at times, characters often have their own idiosyncrasies. I think they are called characteristics.

Characteristics can develop on their own accord, without a script, but maybe not a plan.

Properties, qualities, mannerisms and expressions always seem less contrived when developed from an intrinsic logic, like a candid act. That’s not to say it can’t be learned or observed, it’s all developmental anyway.