One Dark Window by Rachel Gillig
The fantasy world here is so interesting and I found the characters well written. I liked the magical system, though I wasn't quite as taken with the execution of the monster inside Elspeth's head. I understood what the author was doing, but I found him more creepy in a predator way than scary in a monster way, if that makes sense. Still, I thought the story was very entertaining and I really enjoyed the overarching reading experience!