The Centurion by Kathryn Le Veque

A mighty knight known as The Centurion is the man in control behind a powerful liege with dementia, but when his love for a young woman begins to compromise the stability of the Scottish marches, he must make a choice between love… or peace.
Sir Torston de Royans is known on the border as a man of reason, wisdom, and great strength. He also happens to serve a greatly respected liege who slips further into dementia with each passing day. Lord Lionel Harringham believes himself to be a Roman Caesar, and Torston is his great Centurion. Unfortunately, Lord Lionel also commands one of the largest castles in the north and Torston finds himself in a position of not only the protector of the castle known as The Lyceum, but the protector of Lord Lionel’s reputation.

Adding to this stressful situation is Lady Alyx de Ameland. A young woman from an allied family, she has loved Torston for as long as she can recall, but he’s never shown much interest in her. At least not publicly, but privately, Torston longs for Alyx a great deal. However, he cannot think of marriage because of Lord Lionel’s madness. It wouldn’t be fair to bring a wife into the mix of madness that plagues The Lyceum.

But Torston isn’t the only one who longs for the lovely Alyx.
A Scottish laird has his eye on her, too. Laird Douglas Kerr is a man who covets the English lass and does everything in his power to convince Alyx’s father that he would make a good husband for her, but his motives are not honorable. He covets Alyx’s land more than Alyx herself, and as Torston realizes that he can no longer wait to declare his intentions for Alyx, something he has been keeping secret for years finally makes itself, or herself, known… his betrothed.
And she brings hell with her.