Tamira
Asun was a Time Lord from early on in Gallifrey's history.
Appearance
When Mel and the Doctor first encountered her, Tamira had no definitive form, as she was in a state of constant regeneration. After Mel and the Doctor saved her from the Thrusk, Tamira's form stabilised, and she became identical in physical appearance to the Sixth Doctor's companion, Melanie Bush. (AUDIO: Mel-evolent)
Biography
Many years ago, Tamira traveled through the Time Vortex in a Type 2 TARDIS. She was ambushed by the Thrusk, who infected her. She sought to regenerate, hoping to expel them, but instead, the Thrusk froze her in stasis, and secreted her away in the depths of her own TARDIS, inside a dimension within a Space-Time Visualiser.
Many years later, Mel went to investigate the world within the Time-Space Visualiser and discovered Tamira. She and the Doctor made psychic contact with her and discovered what had happened to her.
Later on, the Doctor was able to free her from the Thrusk. She appeared in the Doctor's TARDIS' control room and thanked both the Doctor and Mel for saving her. She then told the Doctor that she would travel back to Gallifrey, and she would keep the secrets of the Type 40 TARDIS safe from the Time Lords of old. With that, she departed back to Gallifrey. (AUDIO: Mel-evolent)