When Darkness Falls: The Palace by Allie McCormack

Ruled by a gracious, wise Sultana, the humans of the great desert city of Al Khair dwell in uneasy peace with the vampires and demons who claim the lands as their ancestral homelands under the leadership of an ancient, powerful vampire. Their shaky truce becomes strained when a young human woman arrives from distant lands. Orphaned since childhood and outcast, Alyssa joins a caravan to the fabled Al Khair where she seeks only to make a new life for herself. A life that quickly becomes complicated when she draws the attention of the Dark Lord himself. A thousand years ago, Lord Damien permitted the humans to build their city. When he senses a new, immensely powerful magical being in the land, Damien suspects the humans of plotting to overthrow him. Furious, he searches for the source of this power, but he cannot stop thinking of the young woman in the tower who had seen through his glamour spell that cloaks him from humans. When he discovers that Alyssa is the mysterious being he has been seeking, his determination to have her for his own threatens to pit the two races, human and vampire, against each other in all-out war. *Please note this is a Trilogy; that is, one sweeping story that is divided into three books. They're not meant to be read out of order, and books 1 & 2 have cliffhangers.