Alphabet of Thorn — Patricia A. McKillip

Deep inside a palace on the edge of the world, the orphan Nepenthe pores over books in the royal library, translating their languages and learning their secrets. Now sixteen, she knows little of the outside world -- except for the documents the traders and travelers bring her to interpret.

Then, during the coronation of the new Queen of Raine, a young mage gives Nepenthe a book that has defied translation. Written in a language of thorns, it speaks to Nepenthe's soul -- and becomes her secret obsession. And, as the words escape the brambles and reveal themselves, Nepenthe finds her destiny entwined with that of the young queen's. Sooner than she thinks, she will have to choose between the life she led and the life she was born to lead...