Hecuba
Hecuba (also known as the Queen of Time) was a powerful being who ensnared sentient beings in games related to time manipulation, with their freedom as the stakes. She was the sister of the Celestial Toymaker. It is unknown if she has any ties to the original Hecuba of Greek mythology, but her name means "far off" and she appeared to have a far away pocket Universe just as the Toymaker.
Abilities
The powers of Hecuba were similar to those of her brother, but while he was fond of games with toys, her games and traps were related to time and clocks. Her pocket Universe was stabilized with her "Great Chronomicon" a giant timepiece trapping the TARDIS in Time and Space. She was very beautiful, wearing the form of a glamourous actress of an earlier age in a luxurious ballgown. Her manner was flirtatious and coy, but she only cared about her amusement in her victims' fear and pain. She was vain, but the Doctor was very sparing with his compliments, knowing she would never have enough. Hecuba was sadistic and enjoyed making the Doctor uncomfortable by encroaching in his space, teasing him, and forcing him to dance with her. She disliked Zoe far more than she did Jamie, perhaps seeing her as a rival, and the majority of her tests required Zoe to use all of her wits. At the same time, she was amused at Jamie, downplaying his intelligence, which gave him enough leeway to solve two of her games.
Hecuba captured the Second Doctor, Zoe Heriot and Jamie McCrimmon, and made them play her games for her entertainment. Zoe and Jamie endured a series of tests with their lives at stake as she toyed with the Doctor over an elaborate and corrupted banquet of spoiling food. Her style of taunting the Doctor was much as the Celestial Toymaker forced Stephen and Dodo to play his games as he played personally with the First Doctor. She implied she had been told of him by another person (her brother), and she didn't understand why the Doctor cared about his Companions (just as the Celestial Toymaker didn't understand how the First Doctor could care about Stephen and Dodo). One of her tests was to stop the Doctor's metabolism. Zoe had to find which of the thousands of clocks was bound to the Doctor's life in order to free him.
The Doctor eventually escaped Hecuba's domain, trapping her in a time loop with her monstrous henchmen Snap and Dragon for the rest of time. She swore revenge on the Doctor as her creations dissolved about her. (AUDIO: The Queen of Time)
Personality
Hecuba was calculating and cruel and found pleasure in "playing" with her victims. Her "favorite part" of the games was watching the Doctor's companions break down in defeat and she loved watching her phantom armies kill each other, though the graphic violence was real enough to sicken the Doctor. Her mood swings could change without warning, turning from snarlingly vicious to laughing at a second's notice. When Zoe first saw her, she couldn't tell if she were laughing or crying. The Doctor never dared drop his guard around her, knowing the slightest slip could be fatal, but he managed to prize small bits of information out of her by "playing" his own game of pretending to be completely ignorant and flustered.
All other visitors to Hecuba's domain had failed or refused to play her games. Hecuba turned them into clocks to keep for her eternal entertainment. She showed the Doctor her past clock-victims, clearly expecting him to be unnerved by the revelations. While she loved games, she preferred to win, and that meant cheat at every opportunity--much as her own brother the Celestial Toymaker did. Her style of cheating was different from his; she "stacked the deck" at every opportunity, giving Jamie and Zoe tasks that she believed would be out of their ability to solve.
Hecuba had a clear awareness of vanity. She cultivated her appearance along that of a "glamour" actress, appearing in a ball gown, bobbed blonde curls and blood-red nails and lipstick like a movie actress. She was amused at Jamie's adoration of her beauty and quick to be jealous of anything Zoe said or did. Because the Doctor failed to respond in predictable ways to her attempts at conversation, she wound up paying more attention to him in turn. (AUDIO: The Queen of Time)
