Fractured Valor by AA DaSilva:

Xavier

After a mission gone wrong, the life of valor I once led bleeds away one drink at a time. But a brother-in-arms from my past needs my help, so I reluctantly agree. The assignment: transport a scientist and her antidote to a base on the west coast for international security.

As we race against the clock and face danger at every turn, I become fixated on more than just the mission. For someone so accustomed to feeling nothing, she makes me want to feel everything.

Isabel

Shaking off the tatted, sardonic hired bodyguard isn’t as easy as I’d hoped. My sharp tongue and defiant nature are supposed to chip away his resolve and allow me to arrive at my destination solo. But my efforts are stirring something in him—something I shouldn’t want from a man like him.

The more protective he becomes, the harder I fight to resist the desires hidden in my guarded heart. Because if I let him in, I don’t think he'll give me back. Especially once he learns I’m the reason he’s lost everything once before.