Millennia

Millennia was the second female member of the Deca, and the lover of Rallon, despite their age difference. In Divided Loyalties the Doctor dreams of his academy days, and stealing a TARDIS along with Rallon and Millennia, in order to travel to the realm of the Celestial Toymaker. This trip ends in disaster, with Rallon absorbed as the Toymaker's new host body, and Millennia trapped as one of his living dolls.

On returning to Gallifrey alone, the Doctor is put on trial and expelled from the Academy, and Millennia and Rallon's names are erased from Time Lord history. They remain with the Toymaker until the Fifth Doctor destroys his realm, releasing them into death.

Millennia is from the House of Brightshore, known for it's wealth and power rather than the intellectual achievements of its cousins. Millennia however has a natural gift for temporal engineering, and the Doctor is certain she will prove to be an exception.