A Court of Silver Flames by Sarah J. Maas

Nesta Archeron has always been prickly - proud, swift to anger, and slow to forgive. And ever since being forced into the Cauldron and becoming High Fae against her will, she’s struggled to find a place for herself within the strange, deadly world she inhabits. Worse, she can’t seem to move past the horrors of the war with Hybern and all she lost in it.