Unbound Queen - M J Scott - Bog

She's been offered a crown but taking it could cost her everything...
Lady Sophie Mackenzie might be fifth in line to the Anglion throne but she never wanted to rule. But she's bound to a demon, gifted with forbidden magic, and under threat from those who would use her unusual power for themselves. And now her hopes of finding peace in exile have been shattered by visions of a terrible darkness gnawing at the heart of her homeland.
Then the emperor of Illvya makes her an offer she can't refuse-return home and overthrow the queen of Anglion, or lose everything she holds dear.
To face down the darkness and save her husband and everyone she loves, she may have to betray the country-and the queen-she once served and play the games of power she never wanted any part of.
But can she play them to win...