Havoc (Havoc #1) by Xavier Neal

When Clint "Grim" Walker, started Operation: Save Haven Davenport, the beaten, bruised girl who fell into his life, he had no idea it would turn him into an unbalanced, enraged, insecure idiot.

The mission objectives seemed simple:
Make her feel safe in his home. Fail.
Protect her from the neighborhood playboy. Fail.
Shelter her from the ex girlfriend. Fail.
Not fall in love with her. Epic fail.

And while Clint could learn to live with those failures, there's one he can't. And that's the objective that matters most. More than his side duties of making amends with his father, more than accepting motherly love from his meddling neighbor, and more than attempting to relate to his brother's in arms off the field.

That objective is life or death.