Dark Challenge

I just started reading Dark Challenge by Christine Feehan. I think this is the 5th book in the Dark series and it is Julian Savage and Desari's story. Here is the summary from the back cover:

They were masters of the darkness, searching through eternity for a mistress of the light...

Was she more than his mate?

Julian Savage was golden. Powerful. But tormented. For the brooding hunter walked alone, always alone, far from his Carpathian kind, alien to even his twin. Like his name, his existence was savage. Until he met the woman he was sworn to protect...

When Julian heard Desari sing, rainbows swamped his starving senses. Emotions bombarded his hardened heart. And a dark hunger to possess her flooded his loins, blinding him to the danger stalking her, stalking him. And even as Desari enflamed him, she dared to defy him - with mysterious, unparalleled feminine powers. Was Desari more than his perfect mate? Julian had met his match in this woman, but would she drive him to madness...or save his soul?