HERE BE VAMPIRES by Debby Feo

The Crusades have spread throughout the realm, and Gaius Domitius Tubero has left more than Roma behind him. Now known as Lord Fearghus O’Glaisne, he has taken up residence in an isolated seaside castle in Eireland.

The endless years and self-enforced solitude weigh heavy on Lord Ferghus and he battles depression. But there is joy amidst sorrow when his extended family comes to visit and wee Kathleen shows signs of being the first female dhamphir born to them.

Fearghus would fight to the death for his family --  vampire, human, and dhamphir alike -- but he succumbs to depression and attempts suicide. Rescued and then nursed by his human stablehand, Sean, Fearghus realizes he must trust this man even further and takes him into his confidence—and his family.

When Fearghus befriends Fionna, a Selkie woman, who teaches him how to swim, he wonders if he dares to love again. So, too, does his grandson, Searlas, who discovers feelings for Fionna’s brother, Bearnard.

Then the castle is violated by a lone knight in search of spoils and the unthinkable happens—Fearghus breaks his millennium-long vow and drinks human blood. As the hunger rages within him, he realizes his family isn’t safe and sends them away.
 
As Fearghus and Searlas’ bond grows even closer, a question remains: Will love—or betrayal—be their destiny?