Who is Miryea from Legends of the Fall and what is their importance?

Miryea was born in Mexico City and later lived in Guatemala and Barcelona. She attended school in Lausanne and Paris. Miryea has the refined tastes of a wealthy woman, but she is cold and neutral in her personality. Graceful and beautiful, Miryea falls for Cochran, and she later becomes the revenge that Tibey seeks. Though she tries through helping the autistic children, she does not escape from her victimization.