I assume you mean the character development of Sylvia, since the other characters are more established and flat. Sylvia develops in her own way, although she never gives the Heron's location to the Hunter, she does become more outgoing. She even grows up a little when she realizes that what she's feeling for the Hunter is love. If only a little girl's crush it still is a far departure from her original feeling of being scared. Sylvia goes from being a girl who avoids every human contact, to one who is comfortable with it, a big change.