“When two characters with opposing agendas meet, you have built-in tension.”
—James Scott Bell, Plot & Structure
The fuel of a page-turner is conflict, and you build in conflict by giving your characters competing goals. Once you’ve assembled your cast of characters, it’s time to think about them in relationship to one another. How is each one going to help or hinder your protagonist in reaching his goal?
To get some perspective on this, create a character web.
Write your protagonist’s name and his goal in the web’s center. On the outer end of each web spoke, write the other characters’ names. ...