Pamela Isley a.k.a Poison Ivy is the tertiary antagonist of Batman: Arkham Asylum, a minor antagonist of Batman: Arkham City and a minor antagonist turned anti-heroine of Batman: Arkham Knight. She is a plant-human hybrid who controls Plants and has chlorophyll flowing through her veins instead of blood, she developed a toxic touch and a pheromone-fueled talent for seduction.
She is voiced by Tasia Valenza.
Batman: Arkham Asylum
In Arkham Asylum, Harley Quinn releases her from her cell as a favor to her friend. Later on, Batman needed to find a cure for the TITAN formula and asked for Poison Ivy's assistance. At first Poison Ivy wanted nothing to do with helping Batman, so she tries to kill him. However, Batman grabbed one of Poison Ivy's beloved plants and crushed it. He threaten that he'll destroy every plant unless she help him with the cure. Ivy then told Batman that there's a plant that contains the spores needed to create a cure. But she also told him that the plants were in Killer Croc's lair.
Before he left, Batman told Ivy to return to her cell, otherwise he'll come after her. Ivy then replied that she'll be waiting. As Batman was leaving the Gardens, Joker ended up injecting Ivy with the TITAN formula. The formula reacts differently with her unusual DNA, greatly enhancing her powers over plants. Having her plants grow more powerful, she causes them to grow up all around the Island causing destruction and deaths of thugs and security guards.
After successfully creating a cure, Batman went back to the Gardens to stop Poison Ivy's Plants from getting too powerful and spreading to Gotham. As Batman made it to the Gardens, Batman was about to inject the formula into the main plant, however, Poison Ivy stopped him from doing so. She also explained that she thought that plants were in pain, but soon realizes that they were evolving. Ivy then summoned a large plant monster and used it to confront Batman. Batman managed to defeat her in the Gardens, using his Batarangs and Explosive Gel to break her shield and cause the Plant she's controlling to fall, then causing the part of the gardens to crumble but Batman escapes to confront the Joker. after the Joker was defeated, the police managed to find a weaken Poison Ivy, extract the TITAN Formula out of her, and place her back in her cell.
Batman: Arkham City
In Arkham City, she has control of one of the buildings with her Plants. Catwoman confronts her, defeats mind-controlled thugs and leaving them to die by her plants. Ivy gains the upper hand and gets her hanging with her plants, but Catwoman promises to look after the flowers inside Hugo Strange's vault. She does find the flowers but kills them in revenge of Ivy attacking her, but decides to blame Hugo if she encounters Ivy again.
Batman: Arkham Knight
On Halloween night, Scarecrow and a military terrorist known as the Arkham Knight take over Gotham City in order to take out Batman. As Batman goes to Scarecrow's safe house somewhere in Gotham, he notices Poison Ivy being tested on with Scarecrow's fear toxin. But it turns out she is immune to the toxin. As Batman asks her what is going on, she reveals that Scarecrow called every villain in Gotham, including her, to the now abandoned Arkham Asylum to hold a meeting on to take down Batman once and for all.
She wasn't interested and Scarecrow had her tested on with fear gas for not going through with his plans. Batman asks her to work with him to take out Scarecrow or else every plant in the city will die. Ivy reluctantly agrees and is taken to the GCPD to stay in an isolation chamber. After Batman sees Scarecrow get away with an ultimate gas dispersing weapon codenamed "Cloudburst", he goes to Ivy back at the GCPD in hopes of creating a plant that can get rid of Scarecrow's gas.
Ivy informs Batman of a plant in Gotham that can be used to dissipate the gas, Batman does manage to locate the plan's roots and free it but than is attacked by several unmanned tanks. Ivy helps Batman destroy the tanks but needed her remaining strength to heal the plant is to get rid of the gas, leaving Batman to destroy the Cloudburst alone.
However Ivy is able to clear some of the toxin allowing Batman to destroy the Cloudburst, following it's destruction Batman saves the Arkham Knight from the tank before it explodes but upon removing his helmet he sees the Joker's face.
Upon this disturbing encounter Batman contacts Ivy telling her he destroyed the Cloudburst, finding Ivy unresponsive. Batman goes searching for her. Batman finds Ivy severely weakened by the Cloudburst toxin, (although Ivy could not be affected by the toxin her plans could be due to her empathetic connection with them she was in turn affected). Batman attempts to save her but is too late, Ivy's last words are that nature will always win before dying in Batman's arms and dissolving into pollen, however with the last of her strength Ivy was able to clear the rest of the toxin and save Gotham.