The Silent are primarily concerned with perfection; created when the Galateid creation rite falls short of the perfection required, they seek to destroy perfection in others, typically maiming, scarring or killing beautiful Prometheans and mortals. They have a taste for strips of skin ripped from a Promethean's face.
The Silent are so-called because they are unable to make a sound. The Word of Creation that animates the Galatea becomes a thing of silence in their Mockery. Where the Galatea are perfection made flesh, the Silent are hideous, twisted creatures, terrifying to behold. They fly on monstrous wings, and the stink of decomposing flesh follows in their wake.
The Silent's dormant form is always that of an inanimate object in human form - statues, sculptures, mannequins, etc - which has been damaged or disfigured in some fashion.