Archangel's Kiss (Guild Hunter #2) by Nalini Singh

Vampire hunter Elena Deveraux wakes from a year-long coma to find herself changed—an angel with wings the colors of midnight and dawn—but her fragile body needs time to heal before she can take flight. Her lover, the stunningly dangerous archangel, Raphael, is used to being in control—especially when it comes to the woman he considers his own. But Elena has never done well with authority.

They've barely begun to understand each other when Raphael receives an invitation to a ball from the archangel, Lijuan. To refuse would be a sign of fatal weakness, so Raphael must ready Elena for the flight to Beijing—and to the nightmare that awaits them there. Ancient and without conscience, Lijuan holds a power that lies with the dead. And she has organized the most perfect and most vicious of welcomes for Elena.