The River's Gift by Mercedes Lackey

Ariella is a young woman who her servants would say is allowed to run wild. Sometimes she stays close to hearth and home, but much of the time she dresses as would a peasant girl and runs off to spend time in the woods, where she heals animals who have been caught by the snares of hunters, or even the claws of other animals. She is so young and pure that all the animals trust her, and come to her hand.

But one day she is approached by what seems to be a very wild and skittish horse who has been injured, she realizes that this "Horse" isn't really a horse, but a fairy known as a kelpie. Merod has been injured by iron and cannot pull out the nail he stepped on, nor can any other creature of fairy pull it for him. And yet, despite his anger and bad treatment of him, Ariella helps him anyway.

When she does so, she finds that Faery has opened to her because she kept her word. The beings and creatures of faery come to her to be healed, and Merod, more mischievous than actually evil, becomes her friend, amazingly enough, and somewhat affectionate as well. He becomes her true friend, showing her his treasures- three wishes gained from the high faery folk and kept until Merod may need them.

Ariella matures among the faery-folk in the forest, going out to heal the people of the manor, whether she has her guardian, Lady Magda's, permission or no, and Merod and the other faery folk are pleased with her efforts- when the people are happy, they do not blame their afflictions on the faeries, and do not seek to kill them, and Ariella enjoys the healing.

But when her father dies after a happy and successful harvest, the Castle is thrown into turmoil and Ariella into mourning. Being female, she cannot inherit or defend the castle, and so she is traded to her closest cousin as his bride, But Ariella, still grieving, doesn't want to marry or leave the castle that has been her home, and she misses Merod deeply. But when she is carried off to her cousin's lands to be his bride, will she find some way to escape this unwanted role, or will she be stuck in an unfamiliar castle as a bartered bride... forever?

Another most enjoyable story, this one a fairytale untold rather than anything like a "normal" fantasy story. But in some ways, it also differs. The characters are more fleshed out, more real and yet it doesn't detract from the fairytale feel of the story. As the two most important characters in the story, Ariella and Merod get the most depth, while the other characters are little more than cardboard cutouts.

Ariella's father is the kindly lord who cares for her people, Magda the chaperone determined to keep Ariella inside and away from anyone she sees as "Lesser". Even the cousin becomes the nameless man who merely wants Ariella for her beauty and lands he doesn't even get a first name- just "Lord Lyon". But even so, by getting inside Ariella's head, Mercedes Lackey elevates the story from a true fantasy tale to something so much deeper.

I found this story a small but satisfying bite that entertained and had a real sense of urgency and peril. In a way, this story serves as a foretaste of Lackey's Five Hundred Kingdom stories and Elemental Mages stories, both of which have Fairy Tale antecedents. Highly recommended.