The Writer He Haunted by H.G. Johnston

Everett and Olivia challenge each other at every turn. Fighting and pushing every button the other has until someone snaps first. They are as toxic as they come, but no matter how volatile they get with each other, they can’t seem to stay away.
It’s more than a payment now, it’s an addiction.

Everett Kingsmen’s favorite assignments were the long ones. The ones he got to work in Colorado Springs, going after people who refused to pay the loans they were given by his father, Malachi Adler.
The assignments often lasted months, giving him the time to settle in and remind the people of the city who the Kingsmen’s truly were.
One customer in particular had forgotten just that, so Malachi ordered his son to remind him who he borrowed money from. Go after the girlfriend, make her pay for the transgressions of her man, and move on.
What Everett hadn’t expected was her mind being just as dark and depraved as his, but he wasn’t like his brothers. He didn’t fall for targets. This was a job, nothing more. Olivia Rose was a means to an end.

Olivia Rose was the daughter of Trenton Lemont, one of the most successful oil tycoons in the industry. She moved away, changed her name, restarted her life just to get out from under her parent’s need for the limelight. She wrote psychological thrillers under a pen name, and lived her life quiet and undisturbed, until, that is, the day she woke up in the basement, strapped to a chair, a man in a mask threatening to kill her if she didn’t pay off her boyfriend’s debt.
She always knew her anger was a problem which was why she did her best to swallow it every chance she had, but this man was something else. He brought it out of her unlike anyone else in her life, and biting her tongue wasn’t an option. So, even when the threat shifted to a different form of payment, she couldn’t back down. She had something to prove now, and no man in a mask was going to stop that from happening.