Her Dragon, His Demon by Julia Mills

When Hell’s Chancellor declares war on their forbidden love, survival isn’t enough—they must conquer or be erased forever.

She never expected to fall for a Dragon, especially one whose touch ignites the fire of passion deep within her soul that she can’t control. He never imagined his Fated Mate would be the Demon who could either complete his soul—or damn it for eternity.
Now Hell’s most ruthless Chancellor has marked them for destruction, unleashing horrors that make death seem merciful. With their bond growing stronger and their enemies closing in, they face an impossible choice: sacrifice their love to survive, or risk everything in a battle that will either forge their Destiny or obliterate them completely.

Some loves are worth fighting for. This one is worth dying for. But will it be enough to live for?