Duality features highly in the movie, Blue Velvet. The film's theme of 'light and shades of gray' is reflected in many facets of the movie. For example, Lumberton is divided between the suburbs and the seedy underworld (with all of its corresponding characters). Dorothy plays a dual role, both as a 'child' to Frank's 'Daddy' and then his 'mommy'. She is both subjugate and oppressor. Dorothy's character has as its 'double' or 'foil' Sandy. The film illustrates the play of light and dark in the human soul.