Maybe your book needs an outlaw.
Outlaws are not always the bad guy, nor are they always gunslingers, though that is what may come to mind. The outlaw and the lawman aren’t necessarily separate or opposite either. Maybe your outlaw tries to go straight, and your cop is dirty.
Your outlaw can be the good guy and save the day or the bad guy out for revenge, which means your outlaw character can be either the protagonist, or the antagonist. If s/he is the protagonist then s/he is a rebel willing to obtain a better world through questionable means. The outlaw archetype speaks out against oppression and challenges injustice. S/he doesn’t conform to social norms. Think Captain Jack Sparrow or Katniss Everdeen.
If your outlaw character is the bad guy, remember that no person, and that includes story people, is all bad all the time. Your bad outlaw character needs some good.
Outlaw characters have had enough of their current situation and will break the rules create change. Just because something has always been done a certain way, doesn’t meant that that is the way you should do it, and consequently and the outlaw will behave in ways that shock other characters out of their complacency. This can make other characters uncomfortable –which means your outlaw character may become a fugitive from justice even if they are a white hat. Think Dr. Richard Kimbal in The Fugitive.
Outlaw characters have also become fairly romanticized stock characters in some fictional settings but with some work and character development, you can create an outlaw character who is unique, spirited, and with their own clear moral code. Note that your outlaw must absolutely have an unbreakable moral code. Think Wolverine or Batman. An outlaw without a strong moral code is just a criminal, most likely. And even criminals have moral codes.
Examples of moral codes:
• A murderer who only murders murderers
• A character who never leaves someone behind
• Someone who will never hurt an innocent
• A character who breaks the law for ethical reasons
• A character who will not let anyone stand in their way
Once you have your character’s strong moral code in place you will have to put that moral code to the test again and again. And your outlaw can not break that code. This will force your character into a corner where there is no easy way out. Especially if the only way out is to break that moral code, which your character can not do.
The outlaw character can be dynamic as the hero/ine, villain, or sidekick. If your story lacks tension, consider adding an outlaw character to your novel, or tweak one of your characters. It will definitely change things up.