whoa,...hm... nothing special. She grows up in the slums of a coast city. The city was rebuild on the ruins of a modern city hundrets of years ago. Everywere in this area (maybe the whole world) spores, gases a and other evil things contaminate the people. The "Injector" (the other concept) is one product of this. ...something like that, a typical apocalypse
it's fine to have some virtual story behind a char conceptart even if there is no cause, because it's practice.