For me, a part of revising is rethinking and reworking my characters. We've been told that characters need to be "authentic," but what does that mean and how do we go about creating these "authentic" characters in our writing? Many authors do these types of character activities before drafting. As stated, I go back to the drawing board once I already have established a very basic draft. It's up to you, but these writing activities do help to strengthen your characters and give them an "authentic" life of their own.
1. Do a written sketch of your character. This means to describe him or her. Don't leave anything out. This goes beyond long hair/short hair, blue eyes/gray eyes. How do you see this character in your head? Does he or she nervously bite his or her lip? Does the character fidget? Does the character slouch? Or is he or she over confident to the point of cocky? If so, describe it. (Remember, this is just for your notes. I'm not advocating putting a one-two page description of your character in your story.)
2. What makes your character unique? This is an exercise to pin down his or her personality. This will help to point out those characters who may fit into stereotypes. For instance, if you described your character as nervous (fidgeting, biting fingernails, twirling hair, biting lower lip), WHY? What makes him or her nervous? Is he or she shy? Maybe this character has something to hide. Work out all the idiosyncrasies to develop what makes your character, not only different, but also integral to the story you are writing.
3. Outline out the relationships between your characters. Is there a love/hate relationship between child and parent? Are there two best friends who secretly have feelings for each other? Is there a reason the antagonist is plotting against the protagonist? By outlining the chemistry between characters (and I'm not just talking about romantic chemistry), you will create depth of characters through their interactions with each other.
4. Now, rewrite. Or, start writing. These characters have a story, and it needs to be told. By having an understanding of each of them, and who they are, they will hopefully become more layered and multi-faceted.
Throughout your writing process and developing of characters, make sure that you are continually reading books. Reread those with rich, in-depth characterization. Learn from them. Have any tips to share? I'd love to hear from you.