Counterpart by Michaela Haze

A world divided in three.
The Light. The Dark. The Lacking.
Ivy Everless doesn’t have a counterpart.
She is Lacking.
When Ivy saves the life of one of the Dark, her world changes forever.
The King of Shadows owes her a debt, one that cannot be repaid easily.
Ivy has no desire to hold anyone’s leash. She has one goal in mind: to make it to the end of her final year at the Universität and qualify as a medic.
When a series of murders, all Lacking, leads back to Ivy, she must find the killer before the killer finds her.
People around her are dropping like flies, and the King of Shadows is her only protection.
But can he protect her from herself?
Being tangled up with counterparts wasn’t her plan.
She’s just Ivy.
Human by day, human by night.
But when one of the Light thinks that Ivy has something to do with the murders, Ivy finds herself caught between the man she saved and the man who wants her to rot in prison.