The burning shadow / Armentrout, Jennifer L.

Evelyn Dasher ran into Luc, the Origin in the middle of the Luxen, and discovered that she and the world of Lux have much more to do with one another than she ever imagined. Still searching for the gaps in her memory and the true nature of her identity, Evie fears that Luc has fallen for her, and, worse, she may be falling for him, even though she knows he is dangerous.

"When Evelyn Dasher crossed paths with Luc, she was thrown headfirst into the world of the Lux--only to discover that she was already far more involved in their world than she ever suspected. Because the Luxen aren't the only ones with a hidden past. There's a gap in Evie's memory, lost months of her life and a lingering sense that something happened, something she can't remember and nobody is willing to tell her"--Book jacket.