Augusta Vradica is the Empress of the New Human Empire. Her real name is Seth Nightroad. She is the youngest of the Nightroad siblings, and the third Crusnik. A member of the Alliance Aerospace Navy, Seth viewed Lilith as a mother figure and holds Abel in great sisterly affection. When Cain was fatally wounded in an accident, she injected him with 100% Crusnik, restoring his life, but changing him for the worse. After he killed Lilith during the war, Seth joined Abel in confronting him and together they succeeded in launching him out of an airlock.
Among the four Crusnik siblings, she has spent the most time with Methuselah, but like Abel, she does not feed on them. Around 800 years ago, Augusta Vradica led the Methuselah to the lands where the Empire would eventually stand, to save them from persecution. She helped restore nature back to the lands, returning them to their former glory before the Armageddon. She then became the Empress of the New Human Empire, ruling over her kingdom as the heart of the Empire itself. As the Empress, Seth is seen as a mother by her people, and treats her subjects as she would her own children. However, most of her courtiers and servants have never seen her before in all the centuries that they have served her, mainly due to the heavy veils she wears to cover her appearance as well as the use of a voice modifier. Though she does age, she still appears as a little girl, but is well over nine hundred years old. It is implied that she does not wish to declare war on the Vatican territories due to her brother's support of the humans. As his sister, she knows Abel very well, and has commented that he is quite popular with the girls for some unknown reason.
During a plot to overthrow her, Seth disguised herself as a tea-seller and a medical student in the human district of the capital city, Byzantium. During that time, she met Ion Fortuna and Sister Esther Blanchett, though neither knew who she was. She later alerted Abel and Asthe when Ion and Esther were in danger, and saved Esther from one of Dietrich's puppets.
When her Crusnik powers are activated, Seth's eyes turn red, her lips turn greenish-blue, her voice becomes deeper, wings styled like fairy-like prop from her back and a pair of giant tuning forks made of blood materialize in each of her hands. In this state, she can almost instantly disintegrate her enemies. Similar to Cain, her power appears be based on a manipulation of sound waves. She calls her technique "The Fire of Sound".
Source: Wikipedia.org
