A Darker Shade of Magic; (Shades of Magic #1) by V. E. Schwab

Kell is one of the last Antari—magicians with a rare, coveted ability to travel between parallel Londons; Red, Grey, White, and, once upon a time, Black.  Kell was raised in Arnes—Red London—and officially serves the Maresh Empire as an ambassador, traveling between the frequent bloody regime changes in White London and the court of George…

An Ember in the Ashes by Sabaa Tahir

Laia is a slave.  Elias is a soldier.  Neither is free. Under the Martial Empire, defiance is met with death. Those who do not vow their blood and bodies to the Emperor risk the execution of their loved ones and the destruction of all they hold dear. It is in this brutal world, inspired by…