Rebecca Yarros’ Onyx Storm introduced a multitude of villainous characters, including the silver-haired venin Theophanie, and even Halden to an extent — but Dain’s father, Colonel Aetos, has quickly become one of the most-hated villains of the entire series. His character proves himself to be corrupt at the end of Fourth Wing when he sends Violet, Xaden, and several others across the wards to meet their deaths — and while he’s somewhat behind the scenes in Iron Flame, it isn’t until Onyx Storm that his truly evil nature is revealed.