Thorn of the Night Blossoms (Children of the Black Lotus)
JC Kang, author
Half-elf Jie and Lilian appear to be mere courtesans of the Floating World, but they are sisters in a clan of assassins and spies which serves the Emperor. When Lilian’s abusive patron makes the work intolerable, Jie sets out on her own mission-to get Lilian reassigned. Problem is, Lilian lacks adequate stealth and combat skills, and her patron, admired by all, holds the key to the empire’s stability. The courtesans have always warred with wits and poetry, but with killers moving within the Floating World and traitors plotting a rebellion, Jie must decide her own loyalty-- to the Emperor or her best friend.