Like a pagan god, Rolfe the Relentless, 28, rode into Castle Aelfgar to claim it as his prize--and Lady Alice as his bride. Lauded for his bravery in France, in England he was the hated enemy. Once ensconced in his new domain, Rolfe became determined to tame the 22 year old Saxon beauty Ceidre, Alice's illegitimate sister, whose spirit and sensuality make him risk treason to have her--not Lady Alice--in his bed...
Mysterious and seductive, she was no lady but a spy for the rebel cause of her noble half brothers. Refusing to bow to this arrogant warrior who ignited her forbidden passion, Ceidre was swept into a dangerous liaison tied to the fate of England and kings. Yet with his kisses on her lips, his skillful hands on her body, she would have to struggle not to surrender to... The Conqueror

Note- The deWarenne Dynasty is very vast and spans through multiple series:
* In chronological order, followed by the books that are distantly related

The Conqueror (deWarenne Dynasty, #1)
Promise of the Rose (deWarenne Dynasty, #2)
The Game (deWarenne Dynasty, #3)
Regency Era:
The Prize (deWarenne Dynasty, #4)
The Masquerade (deWarenne Dynasty, #5)
The Stolen Bride (deWarenne Dynasty, #6)
A Lady at Last (deWarenne Dynasty, #7)
The Perfect Bride (deWarenne Dynasty, #8)

Victorian Era:
A Dangerous Love (deWarenne Dynasty, #9)
An Impossible Attraction (deWarenne Dynasty, #10)
The Promise (deWarenne Dynasty, #11)

Contemporary Era:
House of Dreams

Related books:
Scandalous Love (Bragg Saga, #6)
After Innocence (Delanza, #2)
The Awakening (a novella included in the anthology Heart of the Home)