Here's what I'd do.
A few years before the return of Bruce Wayne, a young talented summa cum laude graduate from Gotham U, with a degree in genetics, a minor in biochemistry and an interest in botany, is hired straight out of university for Wayne Enterprise's GMO department. Unfortunately for the young Pamela, her new boss is more interested in her curvy body than her brilliant mind, as he constantly disregards her suggestions.
As the years roll on, she is constantly reminded of her bosses misogyny, as he will even steal her good ideas and brush of the act as something she should expect in a man's world. But she bites the sour apple, as Wayne Enterprise's GMO department has been her dream as far back as she can remember wanting to help the world.
Then, few few months before Bruce's return, she finds herself at an office party at a harbor bar, surrounded by colleagues. Not terribly bad, but she decides to catch some fresh air, only to find that obnoxious boss out there pawing at a female intern screaming for help.
She breaks them up and the intern runs away with tears in her eyes, only for her boss to turn his attention on her. Resisting, she's promptly told to have some appreciation for being hired, despite him "obviously" being her superior in all respects.
Forcefully she pushes him off her as he grabs for her breasts and he retaliates with a fist to her face, knocking her unconscious so she falls backwards over the balcony, crashing into the icy waters below.
Hours later, she pulls her shivering blue body up from the water, barely alive. And as she collapses in the scrubs, her face plants itself firmly in a large poison ivy plant and despite the burning she doesn't move as her body starts giving up... A labored tiny breath leaves her lips as she seemingly die, only for her body to recoil from the plants burn, her screaming almost like a baby being born. Camera zooms out as she chuckles and whispers "thanks" on the dark Gotham shore.
From then on, Pamela Isley is never heard from again. But a new bio-terrorist seems to start striking all over the globe using infiltration, seemingly unknown biochemical compounds and leaving only a green spray-painted tag spelling "IVY".
And one day, this bio-terrorist sees something while infiltrating a GMO test site in Africa: Her old boss getting an award for his brilliant solutions...
A solution the "dead" Pamela invented while at Wayne Enterprise...
And the award is given by Bruce Wayne, the womanizing playboy...
Within days, Gotham starts experiencing extreme cases of asthma caused by a strange pollen, vegetables and fruits rots in minutes after contacts with some enzyme in the wind and the slums seem to be overgrowing with moss that burns the skin...
IVY has come home, and she's bringing all the money and research she stole while stopping powerful men from perverting her Mother Nature. Not to mention her infiltration skills, which uses every inch of that body to bring men into her power.
In her sights: The most powerful man of all, Bruce Wayne! And the city he loves.