Welcome to the world of The Society
IVI
Imperium Valens Invictum
The story you are about to enjoy is set in the world of The Society created by A. Zavarelli and Natasha Knight.
Although you can read The Sacrifice Duet as a complete standalone, in order to understand the inner workings of The Society, you may want to start with The Society Trilogy (Requiem of the Soul, Reparation of Sin and Resurrection of the Heart).