Being over 120 years old, Purah was already member of the Sheikah Scientists and helped King Rhoam Bosphoramus Hyrule, Princess Zelda, Link and the Champions during the Great Calamity. She was brought a severely injured Link and took him to the Shrine of Resurrection in order to hide and heal him. After Zelda choose to seal Ganon in Hyrule Castle, Impa, Purah, and Robbie decided to separate to ensure at least one of them would survive to aid Link when he finally awoke. However Purah "forced" Robbie escort her to Hateno Village. The doctor then instaled herself in the Hateno Ancient Tech Lab where she worked as director researching Runes to assist Link when he will come back.
Age of the Burning Fields
Dr. Purah's disciples
Over the years Purah mentored Nanna and later Jerrin who was sent by Impa to assist Robbie whom she eventually married. At some point, Nanna returned to Kakariko Village settled down and had a family, though later regretted not heeding Purah's ideas and warnings about the dangers of growing old indicating she was aware of Purah's age reversing research. Though most of the villagers in Hateno Village grew to respect her over the years and respectfully refer to her as the Director, they generally do not bother her and even the elders of the village who lived during the Age of Burning Fields are not aware of the nature of her research.
As she got older, Purah began researching an age reversing rune to strengthen the Hyrulean army to fight the inevitable return of Calamity Ganon. It was during this time that Symin was set by Impa to assist her. Purah would later complain about his usefulness in a letter to Robbie. Her Age-reversing Rune proved fruitful as it reversed her age at first to a Sheikah woman in her early fifties. But she feared she might wake up and find herself in the body of an infant. Her age continued to regress to a woman in her thirties then twenties, later to a teenager, and eventually stopped at the age of a six year old girl. She began working on a Rune to reverse the process, but her Guidance Stone ran out of energy, and she was unable to relight the furnace that powered her tech lab. Symin proved to be unsuited to this task, and she was forced to light them herself. A girl in the village saw her, she was thus forcing her to resort to gas powered lights. When Robbie wrote her a letter about sending his son Granté to study under her, she replied not to send anyone, presumably embarrassed by her current state which is reinforced by her by her choosing to keep her condition a secret from even her own family as neither Impa nor Paya are aware of it.