Ivy, her friend that Shani met in the zone, and some unnamed scientists were either born or turned mutants during or relatively soon after the apocalypse, for some time they conducted well meaning research but their numbers dwindled and Ivy's friend grew jaded, eventually they had to abandon their original base in Old Cairo, Ivy and friend relocate to a more hidden place(the place you visit if you did her story right), some more years pass and the friend grows even more jaded and distant, and Ivy eventually meets Fangs and starts helping the mutants, soon after she gets captured by the decayed on a scouting mission, the MC then either, trades a trinket in exchange for her life, kills the decayed that are holding her, or he jerks himself off as he watches the decayed activate the decap function of the slave collar around her neck.
That's her story up to when you first meet her.