Characters in fiction need some basis in reality or the readers will not suspend disbelief long enough to let you get your story going. Someone you portray as mild-mannered cannot suddenly jump up and stab another player in your drama for no apparent reason, and with no previous indication that your protagonist is capable of such fits of rage.
What if you start your novel with the protagonist committing a murder, before you have established cause? That is a classic maneuver to grab a reader's eyeballs. You've probably noticed it done many times in thrillers and mysteries. The author starts strong and then proceeds to lay out a case that either shows the protagonist to be evil, or to be a person drive over the edge.
How about if you are a lawyer and you are called on to defend a woman who stabs her live-in boyfriend to death for no apparent reason?
There you have your writing prompt for today.
The premise? Taken from real life. Tell the story from the point of view of the murderess or her attorney, and see if you can create a plausible defense for Miata Phelan.
The very pregnant Ms. Phelan has been arrested for murder. Police say she plunged a knife into her boyfriend in the heat of a fierce argument, but crimes of passion are rarely about a single incident. Supposedly, she was angry that he did not buy her anything on a shopping trip when he purchased things for his son and cousin but nothing for her.
According to her sister, Ms. Phelan was being abused by the victim. Do you portray your protagonist as a woman driven to the edge by constant abuse that she cannot find a way to escape? Can you write a narrative that makes a reader believe that a woman just shy of a bachelor's degree could be mentally ground down until she sees no way out? A reasonable person would assume that Ms. Phelan could have walked out of the apartment at any time and taken refuge with a family member, or made her way to a shelter.
Defense attorneys are aware of the narrative arc. The good ones have mastered the art of storytelling, where they convince the jury to suspend disbelief just enough to accept the premise that Ms. Phelan is not guilty of murder, but was driven to lash out in a fit of rage that was induced by the victim.
No wonder lawyers are so good at writing legal thrillers. They pretty much do it all the time.