I had mixed feelings about this book. Mia has survived some horrible abuse and because of that is prickly and slow to trust. Despite that, I did like her and accepted her prickliness because of her past. She still clearly loves her sister and wants the best for her. Mia is working hard to make a better life for them both—hence the asinine plot point about Mia trying to set up a fight with Tray "Fox" Knox (more on the asinine-ness of that in a bit).
Tray is a good enough hero—a rich kid trying to make it on his own because his parents disapprove of his life choices to date—and he and Mia definitely have chemistry. But his actions and internal thoughts struck me as those of someone older and more mature than a 23-year-old.
My major beef with this book, though, was the handling of the MMA-related issues. First, Mia is supposedly this awesome almost-unbeatable fighter and expert in several different disciplines, yet she couldn't have been training for more than about 3 years given her age. This is not realistic. And Tray goes on and on about how he's getting too old for MMA, and he's only 23. Many MMA fighters are older than that. If both these characters had been 5 years older even, the story would have felt more realistic.
Also, it simply wasn’t believable that Mia would think that she had a chance against Tray and, later, the other fighter, unless she was willfully in denial (and she wasn’t presented as that type of person in the rest of the story). Even though she was described as tall, she was far lighter than Tray. And it’s not just weight. Strength makes an even bigger difference. A skilled female fighter against an untrained guy has a chance (as long as weight difference isn’t too great), but a trained female fighter is going to be at a SEVERE disadvantage against a trained male fighter. I’ve done jiujitsu; I speak from experience. A 200 lb body falling onto a 120 lb body with force can do serious damage–so can a single well-landed punch or kick at full power–and once those two are on the ground, the heavier stronger fighter will almost always win (assuming roughly equal skill levels otherwise).
Still I would recommend this book for the two characters and the arc of the relationship between them.