The Pyramid Waltz — Barbara Ann Wright

To most, Princess Katya Nar Umbriel is a rogue and a layabout; she parties, she hunts and she breaks women's hearts. But when the festival lights go down and the palace slumbers, Katya chases traitors to the crown and protects the kingdom's greatest secret: the royal Umbriels are part Fiend. When Katya thwarts an attempt to expose the king's monstrous side, she uncovers a plot to let the Fiends out to play.

Starbride has no interest in being a courtier. Ignoring her mother's order to snare an influential spouse, she comes to court only to study law. But a flirtatious rake of a princess proves hard to resist, and Starbride is pulled into a world of secrets that leaves little room for honesty or love, a world neither woman may survive.