Early in the universe's history, the alien sorcerer X'Hoss foretold the birth of the Designate, destined to elevate all life to greatness. To guide future generations, he created the Illumination Stone, the Map of All-Ending, and the Chalice of Ruins. Billions of years later, Tarene was born on on the Nucleus of Hope, a hidden world fated to be the Designate's birthplace. Like her fellow citizens, she studied to aid the Designate; like them, she was unaware that she herself was the Designate.
In recent years, the mad Titan Thanos obtained X'Hoss's objects of power and decimated Tarene's homeworld. Opposed by the thunder god Thor, Thanos soon defeated him and Tarene wept for Thor's sacrifice. Collecting her tears in the Chalice of Ruins, Thanos received awesome power. However, when Thor took the Illumination Stone from Thanos, the villain was overwhelmed by power and defeated.
Tarene, now aware of her true nature, sought adventure and, using Thor as a template, transformed herself into an Asgardian goddess and journeyed to Earth. As Thor Girl, she became Thor's ally and took the identity of Tara Olson to learn more about humanity. She joined Thor and his allies against the Asgardian demon Surtur, channeling her cosmic power into Thor's father, Odin, who apparently perished while defeating Surtur. As a result of her actions, Thor Girl lost most of her cosmic power. When Thor assumed his father's throne, she remained active on Earth in his place although she has not been seen recently.
Thor Girl's activities following the apparent death of Thor remain unrevealed; however, in at least one alternate future, she will, as the Spirit of the Jewel, reach back in time to empower the alien Desak whose campaign against the gods led him to fight Thor himself.
She is currently enrolled at Camp Hammond with the other Initiative trainees.