Dark Steel by Kathryn Le Veque

The Dark One’s adoptive son, Dane Stoneley, finds his own epic love story in Dark Steel….

1512 – Dane Stoneley de Russe is a hardcore knight, bred for battle. His father, Gaston de Russe, is called The Dark One, a knight so deadly and legendary that he is more myth than man.
Dane has a lot to live up to.
In a nasty battle on the Welsh marches, Dane is forced to make a bargain with the dying Duke of Shrewsbury. On his deathbed, he rewards Dane with his only child, his heiress. Now, it is Dane who will inherit the Dukedom of Shrewsbury and become a powerful man in his own right.
It is a gift that any man would be glad to accept, and Dane is no exception. Except for the marriage part. Focused on the dukedom he will inherit, he gives little thought to the means by which he will acquire it and only on his wedding day does he catch a glimpse of his bride, the Lady Grier de Lara, for the first time.
Then, the situation changes markedly.

Grier is a lovely young woman, raised in a Welsh convent when her mother died, and far removed from her father and his English legacy. Thrust into a marriage she didn’t want, she is nonetheless intrigued with her new husband, handsome Dane. As Dane and Grier come to know one another, feelings develop that neither one of them can admit. When rumors of a Welsh uprising against Shrewsbury began to circulate, it is Grier who decides to involve herself where she doesn’t belong – in her husband’s war plans.
Enter a great world of Medieval pageantry and battles, where love crosses lines and battlefields, and where betrayal is inevitable as two countries remain at odds. Can Dane and Grier overcome the prejudices they’ve always been taught in order to love their enemy?