Ruath Ruathadvorophrenaltid ( Ruatha or Ruath for short ) was a Time Lady who studied at the Prydonian Academy at the same time as the Doctor . She later became the consort of the vampire Messiah Yarven , and tried to take over Gallifrey with an army of vampire s . History . Time at the Prydon Academy . Ruath was in the class of ' 92 , the year above the First Doctor . She and the Doctor used to break into capsules together . The Fifth Doctor said that Ruath had been the first person to lead him astray . After the Academy . Unlike the Doctor , Ruath decided to stay on Gallifrey . She developed an academic interest in vampire s which grew into an obsession . Ruath was part of a research team studying texts from Rassilon ' s time . In a volume of the ROO texts , she found a story detailing how Rassilon was bitten by and converted into a vampire towards the end of his life . With other students of the Undead , she found vampire shrines in the Capitol . She learned of the Vampire Messiah from the Cult of Rassilon the Vampire . She later used Romana to steal a TARDIS , get to Earth and find Yarven . The Prydonian Lady . " " He will be joined by a Prydonian Lady , and the two of them shall cause much suffering . " " - Prophecy of the Vampire Messiah . Ruath became the Prydonian Lady prophesised to help Yarven . She rescued him from the grave in which he had been buried alive . When her plan to give him the Fifth Doctor ' s blood failed , she gave him all her own . This triggered her second regeneration . Shortly after this , Yarven made her a vampire and she became his consort . She worked on a machine that would plunge Earth into a time freeze , creating an everlasting night . When she and the Doctor next met she expressed anger that he had left Gallifrey , feeling she had been betrayed . The Doctor made her believe he wanted to join her cause , letting her turn him into a vampire . Ruath planned to make him her consort once Yarven had sacrificed himself , but she was caught before this could happen . After Yarven and the other vampires were destroyed , she escaped and confronted the Doctor aboard his TARDIS . The Doctor admitted that he had purposefully left Ruath behind on Gallifrey . He believed she couldn ' t handle the life of a renegade , which until then was a decision he hadn ' t regretted . When Tegan intervened , Ruath tried to kill her but Nyssa opened the doors of the TARDIS , and Ruath was sucked out into the Time Vortex . The Doctor said that Ruath was most likely dead . ( PROSE : " Goth Opera " ) Ruath eventually became a member of the gestalt intelligence based in the Vortex called the Horror . ( PROSE : " Dead Romance " ) Personality . The Doctor had known Ruath to be sincere and compassionate during her first incarnation on Gallifrey , but in her subsequent lives she demonstrated little respect for life , allying herself with the vampires and attempting to kill Spandrell . She was a good leader , brave and confident . When her third incarnation got excited , her voice would rise in pitch . ( PROSE : " Goth Opera " ) Appearance . Ruath II was tall and straight backed and bound her long , black hair severely . Her features were sharp and inquisitive . She wore a necklace of golden spheres , a neat black trouser suit and a silver belt with utility packs . When Ruath regenerated , her clothes changed to a red velvet gown with pouches around its waist and matching velvet gloves . Ruath III had long , flowing black hair which reached her waist . Her voice was rich , languid , and full of laughter . Immediately after Ruath regenerated Yarven turned her into a vampire , and she grew fangs . ( PROSE : " Goth Opera " )