Ember Queen

Princess Theodosia was a prisoner in her own country for a decade. Renamed the Ash Princess, she endured relentless abuse and ridicule from the Kaiser and his court. As the rightful heir to the Astrean crown, fire runs in her veins, and a queen never cowers. Now free, with a misfit army of rebels to back her, Theo must liberate her enslaved people. But though the Kaiser is dead, Theo now faces an even more terrifying enemy who has risen in his place: the new Kaiserin. Imbued with a magic no one understands, the Kaiserin is determined to burn down anyone and everything in her way. The Kaiserin's strange power is growing stronger, and with Prinz Søren as her hostage, there is more at stake than ever. Theo must learn to embrace her own power if she has any hope of standing against the girl she once called her heart's sister.