The Empirium Trilogy

When assassins ambush her best friend, Rielle Dardenne risks everything to save him, exposing herself as one of a pair of prophesied queens: a queen of light, and a queen of blood. To prove she is the Sun Queen, Rielle must endure seven elemental magic trials. If she fails, she will be executed...unless the trials kill her first. One thousand years later, the legend of Queen Rielle is a fairy tale to Eliana Ferracora. A bounty hunter for the Undying Empire, Eliana believes herself untouchable - until her mother vanishes.

In the story, two young women centuries apart - one a troubled, magic-wielding queen, the other a bounty hunter serving a ruthless empire - must fight in a cosmic war that spans millennia, only to discover as their stories intersect that they have the power to save their world or doom it. 

Queen Rielle, pushed away from everything she loves, turns to Corien and his promises of glory. Meanwhile, whispers from the empirium slowly drive her mad, urging her to open the Gate. Separated from Audric and Ludivine, she embraces the role of Blood Queen and her place by Corien's side, determined to become the monster the world believes her to be. In the future, Eliana arrives in the Empire's capital as a broken shell of herself.