Firebird by Mercedes Lackey
In Firebird, Lackey draws inspiration from the classic Russian fairy tale to present a marvellous coming-of-age fantasy with a most unusual setting: medieval Russia before unification under the Tsars.
Ilya is the son of a boyar, a Russian prince. In his father's rough-and-tumble household, Ilya is persecuted by his large doltish older brothers, who delight in tormeting him and making him seem the fool. His only friends are three old people: a priest, a magician, and a women who toils in the palace kitchens.
From them Ilya learns faith, a smattering of magic, and the power of love - all of which he will need desperately, for his life is about to be turned upside down.
The boyar's magnificent cherry orchard is visited at midnight by the legendary Firebird - a gigantic, magnificent hawk whose wings seem to be made of flame. Ilya's father and brothers swear to capture the magical creature - but each fails. When Ilya disobeys his father and makes his own attempt to catch the Firebird, he is banished.
The young man journeys through a fantastical RUsia full of magical mazes, enchanted creatures, and untold dangers. Gifted with the ability to understand the speech of animals, Ilya saves the life of a fox, who becomes his most steadfast companion.