She is from Arad Doman.
Theodrin was a wilder when she came to the White Tower. She was originally unable to channel unless a man for whom she had very strong feelings, either attraction or hatred, was nearby. She later overcame this block; a man for whom she had very strong feelings had been watching her train, but one day was replaced by his sister in disguise. When she realized she had been channeling only in the presence of other women, Theodrin was then able to channel saidar at will.
She is very strong in the One Power, stronger than Faolain Orande, who already stands high in the Aes Sedai hierarchy. This has been proved due to Egwene's comparison concerning Amys and Melaine who were "no stronger than Faolain or Theodrin - far from weak". She does not equal Moiraine, since she would then belong to the handful of Aes Sedai able to wield the Choedan Kal, and so she will not belong to the elite of the Aes Sedai, but indeed to its upper tier.
Salidar Aes Sedai Edit
When Siuan Sanche was deposed as Amyrlin Seat, Theodrin joined the Aes Sedai who fled to Salidar, where she continued her training. Since the Salidar Aes Sedai did not have access to the Oath Rod or testing ter'angreal, Theodrin was unable to be raised to the shawl, but instead was granted a special level where she was more than Accepted, but not full Aes Sedai.
Nynaeve's block Edit
When Nynaeve and Elayne Trakand arrived in Salidar, Theodrin was assigned to help Nynaeve break her own block. It was far more difficult than she anticipated, but Theodrin did not stop; she kept trying many different methods.
Theodrin was raised to the shawl by a declaration from Egwene al'Vere as the Amyrlin Seat in exile, along with Nynaeve, Elayne, and Faolain. She chose the Brown as her Ajah. Theodrin and Faolain later both swore fealty to Egwene. Because Theodrin hasn't used the Oath Rod other Aes Sedai still don't count her as one of their ranks. It can, however, be assumed that once she has used the Oath Rod, she will stand quite highly in the Aes Sedai hierarchy due to her strength in the One Power.
Romanda Cassin has decided to take her under her wing and uses her as an attendant. She is actually being used as a spy to report all activities about Romanda to Egwene and Siuan Sanche. She slips Egwene a note informing of Romanda sending sisters to Cairhien, to investigate the news on someone else discovering how to Heal Severing.
The Last Battle Edit
It is presumed she survived the Last Battle.