Michael by Cynthia Breeding

When medieval warlock Michael McCain meets 21st century veterinarian Sophie Cameron, he’s finally met a woman who is immune to his powers. Challenged, he is determined to find out why.
That challenge soon turns to a different sort when a sleeping red dragon is awakened and makes an appearance on the lawn of Sophie’s clinic.

Police, news networks and social media go wild, but Michael knows the Pendragon of Britain only shows up when the sword of fire—known as Excalibur—is in danger of being found by the one-eyed, ancient god, Balor.
Somehow, fiercely independent Dr. Cameron is involved which means she is also in danger. Michael must protect her, but will she let him?