Claimed By Power (Empire of Angels Book 1)

Warrior angel, Cam, was made to kill and destroy demons--not spend days training frustrating, disobedient half-angel, Thea. But he quickly discovers that his new charge isn’t like any other. Powerful in her own right, Thea challenges and intrigues him in ways he never thought possible. And soon, he is unable to deny his urge to claim her.