I've just noticed that there is a Darkest Powers Bonus Pack ebook available:
Contains three companion stories to the #1 NYT bestselling Darkest Powers trilogy.
Dangerous (prequel to The Summoning) The story of how Derek and Simon came to Lyle House, told from Derek's point-of-view.
Divided (set between The Summoning and The Awakening) Derek and Simon's adventures while separated from Chloe and Rae in the factory. Also told from Derek's point of view.
Disenchanted (overlaps part of The Awakening) Simon and Tori continue their journey after Chloe and Derek are left at the truck stop. Told from Tori's point of view.
Please note: these are stories, not novels. Combined, they equal half the length of a Darkest Powers novel.
It's available as epub and Kindle.
My reviews of The Summoning and The Awakening.