Ruath

Ruathadvorophrenaltid (Ruatha or Ruath for short ) was a Time Lord who studied at the Prydon 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 vampires.

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 vampires 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 the Vampire Rassilon. 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. (MA: Goth Opera)

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 she got excited her voice would rise in pitch. (MA: Goth Opera)

Appearance
Ruath II was tall, 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. (MA: Goth Opera)