The Serpent's Bath Water

Amelia never meant to fall in love with a god's abandoned familiar.
She came to the mountains of Kawamori chasing a mistake. Thousands of miles from her quiet, predictable life in Utah, the history graduate student arrived with fogged glasses, an overstuffed backpack, and a thesis topic no professor believed in. The River Serpent God Temple still existed in local records, but according to the world beyond the valley, it no longer had worshipers, caretakers, or purpose.
Behind broken seals and dust-thick air waited a man bound to the shrine by ancient spiritual power, silent and unmoving until her presence woke him. He called himself a Familiar, a servant abandoned by the god he once protected, and he warned her to leave before the temple decided to keep her too.
But Kawamori was already changing. The town was fading in ways Amelia could not explain, the shrine's history refused to stay buried, and the bond forming between her and the Familiar grew stronger with every passing day.
The deeper Amelia searched for the truth about the vanished River Serpent God, the harder it became to separate longing from danger. Loving the Familiar might cost her life. Leaving him might mean abandoning a broken god, a forgotten promise, and a town slowly disappearing into silence.

Note: Though this book can be read as a stand alone, it is a part of the Bound by Blood and Fire Series. There is no specific reading order, nor do you need to read the other books to understand this one, but feel free to if you wish!