The Defining Moment: How Writers and Actors Build Characters

Not every moment leaves a mark. Some pass with barely a whisper. But over the course of a life, a handful of moments leave indelible imprints, shaping characters in ways that form and transform. These may be moments of birth or death, injury or healing, discovery or decision. We speak of lives before these moments and after these moments. Call them defining moments.

In their groundbreaking book, screenwriters and authors Christopher and Kathy Riley introduce and explore the deep insights available to storytellers of all stripes -- from screenwriters to actors to directors, playwrights and novelists -- through an awareness of a character's defining moments. Then they go further, guiding storytellers into a discovery of the storyteller's own defining moments as touchstones for the unearthing or creation of these pivotal moments for their characters.

Meet the Authors

Christopher Riley

Christopher Riley is a professional screenwriter who co-wrote with his wife Kathy Riley the multiple award-winning German language courtroom thriller  After the Truth (German title: Nichts als die Wahrheit). He co-wrote the 2023 romantic comedy  O, Brawling Love! and co-wrote and directed the upcoming family revenge comedy  No Reception. The Rileys have written scripts for Disney’s Touchstone Pictures, Paramount Pictures, Mandalay Television Pictures, Sean Connery’s Fountainbridge Films, and Robert Cort Productions. Christopher produced the action-thriller Red Line and executive produced the web series Bump+. He began his career as a proofreader in the standard-setting script processing department at Warner Bros., a department he eventually rose to manage. He is the former director of the Act One Hollywood Writing Program, the author of the classic screenplay format guide  The Hollywood Standard, an instructor of screenwriting at the undergraduate and graduate levels, a founding partner of  Story Masters Film Academy, and a longtime member of the Writers Guild of America West.


Kathy Riley

Kathy Riley co-wrote the award-winning feature film After the Truth. In addition to her work as a writer for Touchstone Pictures, Paramount Pictures, Mandalay Television Pictures, Fountainbridge Films, and Robert Cort Productions, Kathy holds a master’s degree in public health and is a certified health education specialist. She previously served as vice president of family support for the  Pediatric Brain Tumor Foundationand has worked extensively on behalf of families of children diagnosed with brain tumors. She currently works for Cancer Support Community Los Angeles as associate director of programs. She also holds a certification of professional achievement in narrative medicine from Columbia University, a master’s degree in narrative medicine from the Keck School of Medicine at the University of Southern California, and a master’s degree in public health. She is a longtime member of the Writers Guild of America West.


An invaluable guide for writers and actors on the crucial journey into the heart of dimensional, dynamic characters — and the best ways to bring them to life.”

Sheryl J. Anderson

creator and show runner, Sweet Magnolias

Christopher and Kathy Riley break open screenwriting with the kind of insight that reignites my own love of the craft, both as an actor and a writer.”

Clare Sera

actor, The Princess Diaries; screenwriter, Blended, Smallfoot

The Defining Moment will not only change the way you look at your characters; it may very well change the way you look at your life.”

Bill Marsilii

screenwriter, Deja Vu