As a writer, when you hear these words below, what do they mean to you in direct relation to your book's character(s):
Here's my take on this question:
You are the owner of a taxi cab. In order for the car to transport your passengers from point A to point B all parts must function systematically. If one mechanical part malfunctions then the possibility of stalling is a high probability, thus causing your customer an upset.
Let me now change this to a writing scenario:
You are the storyteller. In order to motivate your reader to continue turning pages of your work, there must be an organized, systematic and coherent (all 3 words are similar in meaning) process of character sketching and growth that makes sense.
Victim of rape:
*one storyteller might show the victim after the assault as withdrawn
*another might portray the victim as a partying type, risk taker
Both are different takes which can be acceptable to a reader as long as the writer authenticates the 'why' in the change of character in direct relation to the assault, compared to the character's personality before that tragic event.
What won't be acceptable is to have no change whatsoever because at that point you risk your reader putting down the book because the emotional connection built up to the point of the assault was made...yet now their connection to discover how the victim will overcome is severed because no change has occurred.
The same applies to your choice of assailant. You must justify something in that person's background/personality to make sense to a reader when details are slowly revealed.
Now, we have psychopaths where there is no rhyme or reason to their actions and a writer might use that as their authentication of their actions. Fine, however, psychopaths do have personality traits that MUST be shown in order for your readers to believe the outcome you've sketched.
You have to have logical character traits that are coherent to their actions that lead up to the book's main event.
Regardless what genre you write, what connects readers to characters and storylines are systematic organizations of fully and diverse traits that are consistent to your players actions, emotions, and dialogue.
Whether you surprise your readers when the villain is finally revealed, they - the readers - should come away satisfied because now they are able to connect all the foreshadows and hints you sprinkled throughout.
To end, all I want to add is avoid 'stick people' because there is no depth, no dimension, and no difference from one player to the next that bonds a reader to a character's plight.