Narrative voice — what your narrator says and how he says it — is a defining feature of young adult fiction. Here are five ways to make your narrative voice teen-friendly, whether your narrator is your young main character or an all-knowing omniscient being:
Embrace your inner drama queen. Use hyperbole, or words and phrases that suggest an overly dramatic view of the situation, its extent, its implications, and its impact on the protagonist herself. "It was the best day ever." "Mom was going to kill me." Many teens lack the experience to put things in perspective, and their stress and frustration often show up as exaggeration.
Relax your grammar. Let sentences purposely run on, double-back on themselves, repeat, and end prematurely for a natural flow. As long as you keep the meaning clear, the grammar police won't come after you. Creative grammar lets you selectively deviate from the rules for a more casual, off-the-cuff, and ultimately youthful quality.
Match sentence structure and paragraphing to your audience. As young people's emotions, intellect, and interests change, a writer's word choice and sentence structure must adjust. Generally, use shorter, more declarative sentences and frequent paragraph breaks for tweens and younger teens so the pages don't seem dense and daunting; slip in longer sentences for rhythmic variety as long as they're direct and active. More complex sentence structure and longer paragraphs tend to convey a more mature voice for older readers.
Embrace immaturity. Young tweens are typically focused inward, with conflicts stemming from that. They're struggling to find out who they are, first and foremost. Don't let young narrators sound too self-aware by analyzing themselves or others. Let them judge and act quickly, harshly, and wrongly — and then face the consequences. Teens are starting to look outward as they try to find their places in the world and realize that their actions have consequences in the grander scheme of life, affecting others in immense ways. Your narrator's observations and commentary must reflect the appropriate youthful outlook for your protagonist and audience age range.
Don't preach. Let the characters embody your message and live your lessons.