Incarnation Saga Book One: The War of the Crystals
The "angelic" royal family of Solaria is full of discord between Lucifer and his younger sister, Selena. With one angel determined to be the greatest and another determined to please the beloved Archangel, Michael, the difference between Lucifer and Selena is like night and day. When Lucifer's wife, Beryl, suggests kidnapping the archangel to blackmail him into giving them almighty cosmic power, Selena has a prophetic vision about her plan and heads her off in a battle to protect him. The end result is a large scale war with consenquences that neither side could have predicted as both Selena and Lucifer are caught between remaining loyal to family ties or fighting for everything angels are supposed to believe in.