Stardark - How Things Could Be (Book 2) Fallen Stars Series

Seren knows the truth. She can feel the steadily growing darkness inside of her taking control and she's afraid. She's afraid of turning into the monster that she's destined to be. There's hope though. There's a small glimmer of light in the darkness. The only problem is that the light holds as many secrets as the darkness. When the secrets start to come out, Seren realizes that even the good guys aren't always good.