Honorable Darkness: Story of Hex and Snip - The Realm Series, #9

Legends claim they are a pair born with souls so tarnished that they steal all the light and happiness from those who dare cross their path. Revered as beings of myth and legend, they are the first twins born in the Realm for eons. They have become the monsters parents warn children about when they misbehave. Many of the kingdoms see them as a dangerous abomination. Authenticity has been lost in time, leaving only the twisted and embellished tales of the impossible twin princes that had everything but desired more.
After the significant loss of their mother, their only source of joy was their sister, Evie. But when she is taken under mysterious circumstances, the twins clash with their father, each other, and the rules of life itself in an attempt to save her life. When it comes to the truth of their lives, Hex and Snip find themselves wishing the twisted stories of their past were true. For the truth is much, much worse.