Kushiel's Justice — Jacqueline Carey

My blood beat hard in my veins and hammered in my ears, like the sound of bronze wings clashing. And I understood for the first time what it meant that Kushiel, the One God's punisher, had loved his charges too well...

The son of Terre d'Ange's most infamous traitors and the adopted son of its greatest champions, Imriel de la Courcel returns from his year at university a little older and a little wiser. But perhaps not wise enough. He and Sidonie, the Queen's daughter and heir to the throne, begin a torrid, forbidden affair--until Imriel's obligation, as a royal family member compel him to marry an Albar princess. By choosing duty over love, Imriel and Sidonit transgress their religion's central precept: Love as thou wilt. And when dark powers in Alba, who fear an invasion by Terre d'Ange, seek to use the lovers' passion to bind Imriel, the gods themselves take notice.

Before the end, Kushiel's justice will be felt in heaver and on earth.