The Fall of Delajen — Seth Giolle

Jeann has taken to Shadow. To save those she loves, she accepted a darkness too terrible to conceive. And is now slowly succumbing to its will. The world has taken to the hunt with a war between human and dragon looming.
In Book 4 of The Call of the Lucherne Suns, her friends must find a way of freeing her from the grasp of darkness or risk facing a foe unlike any they've ever seen before!
And she was the person who defeated the Shadow Creature in the Veshod, not them.
She is their friend, and maybe soon their greatest nemesis. Evil knows no shape when it's bathed in shadow.