Growing up in a small island named Dile, Audrey's parents died at an early age and her brother left as soon as he could, so Audrey grew up with family friends, who sort of let her do her own thing. This lack of guidance in combination to an introduction to a strange infestation brought to Dile allowed Audrey to learn about the toxicity that invades so much of the world. She knew it could be manipulated into good use. Combine this with the art of hosting, that is to manipulate a form of matter into the control of a person, and Audrey became a problem to the town, who deemed her dangerous and foolish. 

Eventually the mold started to manifest too much of the island, and what started as a fixable problem became worse with Audrey's attempts to control it. Ultimately the island had to evacuate, and Audrey did so as well, in shame. 

The citizens of Dile made their new home in a village in Evelow, a huge city in the mainland that was much more advanced and didn't seem to stop growing. Audrey didn't live in this village, however, and started a new life on the other side of the city, in a district much too small to gain notice. She kept a vile of the mold that she wears around her neck, as she never lost hope that she, and it, could help each other out. 

She would eventually befriend her roommate and the other inhabitants of her living quarters, but she would keep them at a distance in order to prevent them from ever learning what she dealt with.

When Evelow's sweetheart Aurora Vespira gains possession of Audrey's vile, Audrey escapes back to Dile in order to get more from the source (and to avoid Evelow's authorities, as hosting is forbidden there). In Dile, the mold has gotten bigger and has sentience, in which Audrey names it 'SOUL'. To understand SOUL, Audrey decides to quite literally be its host. 

She does decide to return to Evelow in order to reunite with her friends which she regrets being so distant toward, but she accepts she'll have plenty of problems to face there.