One of the best things you can do as a writer is to keep your reader guessing. Guessing readers turn pages to see if their suspicions are correct. Readers who have all the answers spoonfed to them close the book, turn out the light, and go to sleep. Then, it's anyone's guess as to whether the book will ever see the light of day again...
Last night, at the Novel Writing Practicum, I suggested that writers think of their narrative as a game:
• Too predictable = too easy. Reader grows bored and stops.
• Too unpredictable = impossible to win. Reader grows frustrated and stops.
• Establish the playing field & the rules early.
• Adhere to the rules you set.
Part of establishing the "playing field" involves clearly placing your book in a particular, recognizable genre. Another aspect of the "rules" has to do with the decisions you make about things like reality and narration (First or third person? Omniscient or narrow? Biased or objective?).
The readers’ fun is in thinking they know more than you.
Your fun is in surprising the readers AND keeping them turning pages.
The writer's toolkit of surprises includes such gems as:
• Narrative sleight of hand and misdirection.
• Unexpected emotions or actions. (Think Scarlett in "Gone with the Wind." Any vulnerability comes a a surprise, which brings added depth to the moment.)
• Reveal of previously hidden information.
• Characters acting in ways contrary to their nature. (In a wonderful scene in Being Julia, the main character -- a diva -- goes out of her way during practice to allow the ingenue to shine. The entire scene is memorable because it includes one surprise after another. What makes it even more effective is when the diva allows her true nature to shine -- in a scene that is also rife with surprises.)
• Previously introduced but now forgotten element takes center stage.
• Unexpected alliances or feuds.
• “One fact short of understanding.” (Excellently played out in thrillers -- Shattered (or "Butterfly on a Wheel") and The Illusionist are two films that use this method very well.
“Let the audience add up two plus two. They’ll love you forever.” Billy Wilder gave his mentor Ernst Lubitsch credit for emphasizing surprise in the game of storytelling.
It should come as no surprise, however, that the more you engage your readers and give them a puzzle they can sink their teeth into, the sooner they'll come back to you for more!