Everyone who has completed high school English knows grammar is a system of rules defined as:
a. The study of how words and their component parts combine to form sentences.
b. The study of structural relationships in language or in a language, sometimes including pronunciation, meaning, and linguistic history.
Most creative writers understand that the use of grammar is more a guideline, rather than a frigid regime to be slavishly obeyed. A fiction writer's style has a confident and familiar relationship with grammar, but a good writer knows that sometimes the seemingly wrong combination (grammatically) achieves precisely the intended affect.
My particular favorite is the run-on sentence. If you're a technical, business, scientific or analytical writer, or just a person who thrives on structure and learned rules, than this will drive you insane. However, before yanking out the highlighter and pointing to a writer's blaring mistakes, take note that some of literatures most revered and studied authors broke the rules to create a unique voice. For example, authors Cormac McCarthy, Henry Miller and Virginia Woolf were masters of the run-on sentence. Woolf's creative ability to string over a hundred words together invented an entirely new writing style termed, 'stream of consciousness.' Grammatically, her writing was incorrect, but creatively it was original and poetic.
Why use a run-on sentence? It provides a lucid, intelligent and musical quality to a scene. Specifically, the run-on sentence is utilized by creative writers to describe setting, a journey or even relay intimate thoughts. It can also build suspense and enhance emotions such as panic or boredom. The run-on sentence can increase or decrease tension within a scene and create a feeling of calm or chaos.
I'm convinced that most fiction writers understand the rules of grammar, but often choose to stretch and play with them in order to give voice, style and creative affect to their stories. If I listen to some of my critics and shore up my work to neatly fit modern English constraints, then I wouldn't be a creative fiction writer. I'd be stuck in an office cubicle spitting out technical jargon and cc: memos about newly implemented policies.
I encourage readers to open a novel and have a look at the run-on sentences littering the page. Just for fun, choose a sentence that might benefit from a grammatically incorrect, liturgical rhythm and play. Rather than correct, shorten and neaten it, really let the words rip. Exercise your paratactic muscle, and your ampersand key, and connect rather than disconnect with the art of language.