Dr. Pamela Lillian Isley was a botanist who led a secret life as the eco-terrorist Poison Ivy. Unlike most of Batman's rogues, she had little interest in money or power unless she needed them, instead being obsessed with preserving plant life and taking revenge on those who she believed had harmed it. Her ruthless methods frequently landed her in Arkham Asylum.
Holding a PhD in botany from Gotham University, Pamela Isley was once employed by Chez Gerard, a cosmetics firm, as a research chemist in charge of developing new perfumes. She also offered a weekly lecture series at the university on rare and extinct plant species.
At some point, Pamela dated District Attorney, Harvey Dent, who was taken with her. Unbeknownst to him, she had marked him as a "murderer" for his part in arranging the excavation of land for the future site of Stonegate Penitentiary. The excavation had involved bulldozing a field of wildflowers, including a rare wild rose that would have gone extinct had she not saved it first. Appropriately, she used extract from the rose to create a rare and deadly poison, which she administered to Dent through a deep kiss. He fell into a coma and was not expected to live. A personal friend of Dent's, Bruce Wayne investigated the crime as Batman. Discovering the origin of the poison, Batman confronted Isley, who now called herself "Poison Ivy". In the ensuing struggle, Batman captured the rose as a "hostage", forcing Ivy to surrender the antidote she had developed. He managed to save Harvey's life, and Ivy was imprisoned in Stonegate. She was later transferred to Arkham Asylum.
Months later, having escaped or been released, Ivy opened an all-natural resort spa outside Gotham, under the alias "Dr. Daphne Demeter". The "Eternal Youth Spa" was a bait through which Ivy attracted wealthy business men and women guilty of certain environmental crimes, and "treated" them with plant-derived toxins, which transformed the people into plants themselves. By unfortunate coincidence, a greedy Wayne Enterprises executive had made a deal with a South American company to level a section of the Amazon rain forest, before Bruce aborted it. Ivy targeted Bruce for his perceived part in the deal, and Alfred Pennyworth attended in Bruce's place for a free spa getaway. When Alfred disappeared, Batman quickly deduced the doctor's true identity, and stopped Ivy's plan yet again.
After another escape, Ivy was arrested at the Stacked Deck, over a poker game with Joker, Penguin, and Two-Face. Before the game, she exchanged a few amused reminiscences with her "old flame", Harvey Dent (the amusement was entirely one-sided).
A chance meeting during a heist at the Gotham Museum sparked one of Poison Ivy's most unique relationships. Harley Quinn, recently evicted from the Joker's gang, helped Ivy escape the clutches of the Gotham Police Department. Though the personalities of the two seemed completely opposite, their (somewhat) common goals bonded them into a formidable duo. Harley seemed to thrive on the experience of an honestly affectionate partner, while Ivy admired Harley's streak of fun and ingenuity, though she was exasperated by Harley's unshakeable devotion to "that psychotic creep" (Joker). Shortly after uniting, they took Gotham by storm with a crime spree. Dubbed "The New Queens of Crime", their actions went unstopped for a long time. Despite his best efforts, Batman was unable to capture the two damsels, and only after their home was destroyed by the Joker were they captured by Renee Montoya. Still, the bond had been forged. Unlike most villain team-ups, Harley and Ivy seemed to have a genuine friendship, as each helped the other with problems, be they personal or other.
After failing to meet the psychological requirements for rehabilitation, Ivy returned to Arkham and was present for the Trial of Batman. She acted as a juror and as a "witness", testifying towards Batman's involvement in her turning to crime.
Months passed, and for the first time, Ivy seemed to have returned to a normal life. Released from Arkham, Pamela Isley moved away from Gotham, married her psychiatrist, and embraced his two children as her own. Despite strange plant-related occurrences occurring, Batman and Robin were unable to link any connection to Isley. Unfortunately, Ivy had merely fooled the Dark Knight and Boy Wonder. Creating plant monsters to act as clones of her "family", Ivy had not only created a legitimate front for her activities, but also made a small drone factory. Though Batman and Robin once again foiled her plans, Ivy escaped.
Later career in crime
Though each pursued their own area of interest, it was not uncommon for the Ivy and Harley to team up, share a hideout, or rendezvous for the holidays. When Livewire was transferred to Gotham for further psychiatric treatment, a brief and unlikely trio formed. Though they initially subdued the two with certain ease, the combined forces of Batgirl and Supergirl proved too much for the electric charged trio given their lack of coordination, as Livewire's lightning almost burn Ivy's plants, so she stopped to fight to save them.
Ivy and Harley had many other capers, including various robberies, some holiday fun, and occasional turmoil amongst themselves. Throughout this time, however, their relationship nurtured, and it seemed the two fostered a general care for one another. At one point, the men of Gotham disappeared altogether. Ever the opportunists,the two raided the Gotham Police Department Special Crimes Dangerous Evidence Vault, stealing items from various villains including the Penguin, the Joker, and Mr. Freeze. The two fled to the Gotham Monastery, Batgirl and Catwoman (who was the prime suspect in the men's disappearance) attempted to reason with the two, but Harley accidentally discovered the true cause of the male disappearance: a weapon designed by Mr. Freeze.
Renee Montoya and the GPD arrived to arrest the women. Harley and Ivy escaped, but were branded accomplices in Catwoman's supposed crime. Gotham went into a hard lock down, but eventually the four women united. Donning a Batgirl outfit, Poison Ivy broke into a warehouse in Gotham's West District. Unmasked, she managed to evade capture long enough for Batgirl to discover the true cause of the disappearances: Dora Smithy. After the mystery was resolved, Harley convinced Catwoman and Poison Ivy to turn themselves in, as they had promised to Batgirl. However, they made no assurances that they'd stay captured, and the three escaped.
Eventually Ivy found herself lacking in funds. Trying to gain more foundings, Ivy created "perfect" mates for rich socialites, who would then kill their spouses and inherit their fortunes. Between her creations was Susan Maguire, who married Bruce Wayne. Although Tim Drake and Barbara Gordon were happy for Bruce, Dick Grayson remained suspicious of Susan, and completely disbelieved that Bruce would be capable of giving up his life as Batman. Due to this, though unknown to her, Bruce nearly gave up his Batman identity until Batgirl and Robin discovered the truth and figured a way to kill her plants creatures. These events later resulted into a fight with Batman and his partners in the honeymoon, which happened in a luxurius boat, before sinking into the ocean.
Having survived the boat's collapse, Ivy later teamed up with Harley again in another attempt to gain some quick funds. Because of the "Big Bang" in Dakota, new metahumans had been created, several of whom were uncomfortable with their new-found powers and transformations. Through the internet, the two set up a mock therapy and treatment group, and began contacting the "Bang Babies". One of their victims, Nails, was a student at Dakota High. Thinking she was heading for help, she discovered she'd been lured into a life of crime. Though they convinced Nails to aid them in their plan (this time pilfering a shipment of gold from a cruiser), Static (who had followed Nails to Gotham) and Batman halted the scheme and captured Harley and Ivy once again.
Abilities and equipment
Ivy is a genius chemist. Combined with her botanical background, she frequently concocts plant-based poisons, toxins, and serums designed to kill, transform, or protect, depending on her purpose and needs. Later in her criminal career, Ivy also had the ability to secrete potent pheromones that could make her (or her plant creatures) irresistible to men.
In personal combat, Ivy is a skilled gymnast and carries a miniature repeating crossbow on her right wrist, which she typically uses as a last resort—at least against people, since it's also useful for puncturing tires.
In the original series, Poison Ivy's abilities are somewhat more mundane than they are in the comics. In the comics, she is a metahuman villainess who is herself part-plant, able to communicate telepathically with plant life, and capable of synthesizing chemicals from her body at will, either as deadly poisons or antidotes to same. Ivy's favorite means of transmitting these poisons is via a kiss, which the animated version pays tribute to. In The New Batman Adventures, her abilities are closer to those of her comics self.
The Harley and Ivy relationship is one of the few villain team-ups that seems based around friendship, rather than mutual gain. This is likely why the duo persists where others fail. "Red", the nickname typically used by Harley Quinn for Ivy, was actually first used for her by The Joker in "Joker's Wild". The Batman Adventures Volume 2, set during Justice League Unlimited, showed that after the events of "House & Garden", Pamela created a copy of herself in order to provide herself with a means of escape by distracting Batman, as well as to keep Harley company while she herself left Gotham to live with Doctor Alec Holland. This retcon was never adopted in the animated series, though it is interesting to note that the Poison Ivy of the Justice Lords' universe has a considerably greener skin tone, a change that appeared in The Batman Adventures vol. 2, as well as the Timm-Dini miniseries Harley & Ivy.
During the development of Batman: The Animated Series, Paul Dini originally pitched an story for an episode involving Poison Ivy seducing Swamp Thing. However, the idea was scrapped when the rights of Swamp Thing were found unavailable. However, Dini's idea ended up being developed into what ultimately took shape of the non-DCAU series Justice League Action episode "Garden of Evil". Also, during the running of Justice League, the show's writers pitched several story ideas for episodes featuring Poison Ivy, but Bruce Timm rejected them because he wanted to explore new characters and storylines.