Poison Ivy | Queen B

Botanist Pamela Lillian Isley was transformed into a plant-human hybrid by a science experiment gone wrong. With chlorophyll flowing through her veins instead of blood, she developed a toxic touch and a pheromone-fueled talent for seduction.

Her crimes became more ecologically focused as she had increasingly abandoned her human side and identified more with the natural world. Her unique brand of eco-terrorism often put her into conflict with Batman, whose iron will usually protected him from her seductive powers.

She is Harley Quinn's best friend, eventual girlfriend, and fellow Arkham Asylum escapee.

Ivy became the CEO of the Legion of Doom, but she eventually realized it interfered with her real goals. She defected from the Legion of Doom and later became a member of the newly created Gotham City Sirens, which disbanded sometime before the beginning of due to the teammates' inability to work together.

Since her encounter with the Dark Knight on Arkham Island, Ivy had been transferred to Arkham City. After she took refuge in a vine-covered stronghold, Ivy kept humanity away rather than participating in the gang wars of Arkham City. Her presence would go unnoticed until Catwoman sought her out. There, she began plotting destruction for Gotham. Months later, she helped Batman eradicate Scarecrow's Fear Toxin by sacrificing herself. A small plant would start to grow from the pollen-like remains of her body,

Poison Ivy is a young tall woman with an hourglass figure, green skin, green eyes, and green lips. She has long, waist-length red hair, styling part of it on the left side, almost covering her eye; the look may have been inspired by the hair of Poison Ivy's redesign in the DC Animated Universe, specifically in The New Batman Adventures and Static Shock.

Most of her outfits heavily favor green. Her usual look is a dark green jacket and a white tank top underneath it, with green tights/pantyhose with a pattern of leaves and lines on them, and black high heels. For pajamas, she wears a long-sleeve T-shirt reading "Tree Hugger" with green sleeves, plus green pajama pants. In the cold, she sometimes wears a beanie with a pink flower print on it, notably when at Mr. Freeze's lair. Many of Ivy's accessories are colored green, including a green sunhat, green sunglasses (in "Bachelorette"), green scuba goggles, and a green bikini (in "L.O.D.R.S.V.P.").

Ivy normally acted with air of calm calculation; however, this will collapse into distress if she feels as though her beloved plants were threatened. She exuded confidence with a sultry tone of voice. Her strongest traits were generally a love for mother nature, and a hatred for humanity, which endangered it.

Ivy is reserved, pragmatic, sarcastic, and misanthropic, usually controlling her emotions unless pushed. Though she is quite affectionate and understanding towards people she considers friends, Ivy has severe difficulty forming such friendships due to abandonment issues. Her hatred for humanity stems from her childhood, stating the first time her father hit her; this only changed when she met and eventually befriended Harley Quinn (then Doctor Harleen Quinzel). Besides Harley, Ivy's other close friend is Frank the Plant, a Venus flytrap she brought to life. While he and Ivy often needle or tease each other, their friendship has lasted 20 years; Ivy has said Frank was the only person to understand her before Harley entered the picture.

Her primary love is for nature, and she focuses her criminal pursuits on obstructing any efforts to harm the environment or plant life. While Ivy and Harley are both geniuses in their scholastic fields (biochemistry and psychiatry, respectively), Ivy is a diligent biochemist and has used her knowledge within that field in her eco-terrorism. She also likes the band the Indigo Girls, jazz, reading, and fighting/killing people who she deems deserve it. Despite being an introvert, Ivy has a hidden fun-loving side; she seems to dance when there is party music around.

Ivy would develop a relationship with Kite Man. Although she initially held him in contempt, flying together on his kite over Gotham City slowly began to warm her to him. When they started dating, she tried to hide it out of shame, but eventually admitted to being his girlfriend. They would later get engaged, but by the time of the wedding, Ivy realized her heart wasn't really in it, and she had just been going along with it all out of fear and desire for a stable life.

Ivy's relationship with Harley began when Harley was working as a doctor at Arkham Asylum where Ivy was incarcerated. As her therapist, Harley helped her deal with her misanthropy. In return, when she saw Harley being abused by the Joker, Ivy took it upon herself to help Harley out of that abuse, gradually getting Harley to realize how toxic her relationship with the Joker was. Ivy protected her at any cost and was deeply hurt when Harley relapsed. This resulted in Harley becoming Ivy's greatest fear, specifically allowing herself to trust someone only to be abandoned. However, Harley would change for the better, freeing herself from Joker's spell, winning back Ivy's friendship, and later on, her love.

Even though Ivy is a cautious introvert and Harley is an impulsive motormouth, the two love each other dearly. Their romantic relationship is built on a shared history, familiarity with each other's likes/dislikes, mutual respect, a desire to see the other succeed, and unwavering chemistry (they "get each other").