Thinking of submission/dominant relationship but also that has actual love involved. I may be explaining this badly.
a girl with magical powers has been past around from one man of power to another. She can be a wild spirit but with the right thing she can be tamed. Often past on due to her refusal to use her powers.
the guy is the leader/king/ruler of a barbarian type empire, he bigger in muscle mass than most of her previous owners. However their relationship may start eventually hopefully he will see something in her and begin to fall for her.
Maybe he drags her around everywhere he goes not wanting anyone else to touch or speak to her. Maybe he thinks branding her will tame her.
any ideas are welcoming