Fairy Queen, book 1.5: Of Fire and Ash
Amber Argyle2016

One promise can change everything.

The fairies must never know of Nelay’s sight, for the attention of such dark and terrible creatures brings more things dark and terrible.

But when Nelay's father is near death, the fairies are the only ones who can save him. All they require is a simple promise that she'll return the favor one day.

Sometimes promises are deadly.