The Demon Prince - Ars Numina, #2

Charming. Irreverent. Haunted. Alastor Vega is the sole challenger in a brutal battle for succession. Against all odds, he must stop his power-mad brother, Tycho, before he destroys the Numina. Though he never wanted to rule, he must claim the throne and liberate his people, or the consequences will be calamitous. Yet only the surprising support of a beautiful Animari doctor gives him the fortitude to fight.
Focused. Analytical. Solitary. Dr. Sheyla Halek has always been more interested in research than personal contact, but family ties-and the needs of her pride-keep her in Ash Valley, deferring her dreams. Brusque and abrasive at the best of times, she never expected to bond with anyone, let alone Golgoth royalty. Strangely, Alastor seems to need her as no one has before, and not only for her medical skills.
Their attraction is forbidden, likely doomed beyond the wildness of wartime, but these fires burn too hot and sweet to be contained.