Born in Flanders under the name Irene, she was a prostitute who managed to be accepted as a courtesan. After she had bedded many influential members of the Flemish court, she came to the notice of Goratrix, who saw in her both inherent magical talent as well as talent and dedication.
He took her with him, giving her the name Therimna, and making her his lover. After she was introduced into the Order of Hermes and even had bedded Tremere himself, to show Goratrix how easy it was to change patrons, she gained effective immortality due to hermetic magick. She began to specialize herself on alchemy, traveling across Europe and eventually settling in Ceoris.
When magic began to fail, Therimna was horrified, searching madly for a solution to this problem. When she noticed a change in Goratrix, she begged him to share his secrets with her, which he did after a while. Reveling in her undead nature, Therimna began to hunt those magi who came too close to the truth of the undead secret society that developed. In the face of the many dangers the early Clan Tremere was forced to face, she eventually lost hope and began secret negotiations with the Tzimisce.
She also started to search for allies among the Ventrue and Lasombra, all the while fearing that her scheme would be thwarted. Her thaumaturgical researches into alchemy also opened the possibility to break the Blood Bond, thus freeing her from the Pyramid.
When her schemes were discovered, she was cast out of the Clan, wandering across Europe under the guise of a Tzimisce, hunted and shunned by her former peers and would-be-allies, up to the Final Nights.
Therimna's hair is patchy and discolored from dozens of chemical accidents suffered over the years. The skin of her hands is perpetually raw and flaky. She shows little concern for dress. Her robes are both tatty from overuse and stained from the laboratory.