The beholden
(Book)

"Two sisters, a pregnant aristocrat and a scholar-magician, and themselves at the center of a conflict between the immortal being Decay and the Emperor himself . . . Orphaned as young women, Celestia and Izara De Malena are land-rich but destitute, with only a failing rainforest acreage, Celestia’s perfect manners, and Izara’s nascent magic to their aristocratic names. With their money running out, Izara summons the Lady of the Seraphine to demand a favor: a husband for Celestia, one rich enough for the sisters to keep their land and restore their family name. But a favor from the river goddess always comes at a cost . . . Five years later, as war and disease spread across the land, the Emperor calls Celestia’s husband away on a secret mission and the Lady returns to collect her due. Izara is forced to leave the academy where she studies to become a mage; Celestia is pulled from her now-flourishing farm while pregnant with her first child. Together, they must repay their debt—embarking on an impossible quest that pits them against Celestia’s husband, the Emperor, and a god even more powerful than the Lady of the Seraphine." --publisher's website