The Saint and the Demon by Teri Santitoro and Ron Sparks
In the not-too-distant future, a young reporter reluctantly agrees to interview an aging, senile, old man in the heart of the Florida Everglades. In the humid, swampy environment, the reporter is sure that there can be no story of substance to report here, but the old man reveals that, in the past, his love was so strong and so passionate for a woman that he stopped at nothing to get her back when the forces of war tore them apart. He became a hero and a coward. A lover and a fighter. A saint and a devil. In his quest to rescue the woman he loved, he turned into something that she could no longer love.
Into the middle of this personal ordeal tumbles Cutter, a man from another world, sent to Earth to establish a breeding mission for his endangered race. He falls in love with an Earth woman, and must defend not only her, but also the future of his own people. The object of his alien affections, a young woman named Angel, finds herself suddenly thrust into a world of aliens and intrigue, and of a love that has far more dangerous consequences than she could possibly have imagined.
Santitoro and Sparks draw you into a world where the lines between friend and foe blur until Cutter and Angel cannot even be certain of each other. If one race has to die so that the other may live, who gets to choose? Cutter? Or the woman he loves? Or will the choice be taken from them by others far deadlier and far more powerful?