Divine Rivals by Rebecca Ross — book slip

After centuries of dormancy, the gods have awakened to wage war, but eighteen-year-old Iris Winnow is more concerned with keeping her family together. Her mother struggles with addiction, and her brother is missing on the front lines.

Iris's best hope lies in winning a columnist position at the Oath Gazette.

To cope with her worries, she writes letters to her brother and slips them beneath her wardrobe door, unaware that they are mysteriously reaching Roman Kitt, her aloof and handsome rival at the newspaper.

As they exchange anonymous letters, a profound connection forms, leading Iris to the war's front lines in search of her brother, the fate of humanity, and love.

For fans of Shadow and Bone and Lore.