Physical Description

Hair

Blonde

Eyes

Blue

Height

5 ft 7 in (1.70 m)

Weight

140 lbs (64 kg)

She trades her traditional jester suit for a tight, utilitarian nurse's outfit, complete with pigtails, a nurse's cap, and a distinct lack of proper asylum-standard footwear.

Personality

Obsessive Devotion: Her defining trait is her unyielding, almost blind devotion to the Joker. Even though the Joker frequently manipulates and abuses her, she believes she is deeply in love and will go to any length to win his approval.

Unpredictable & Homicidal: Beneath her cheerful and teasing facade lies a homicidal psychotic. She can switch instantly from a playful, childlike demeanor to ruthless violence.

Intelligent but Blinded: Before her corruption, she was a highly trained, bright, and capable psychiatrist. While she retains her sharp intellect and knowledge of psychological manipulation, her extreme emotional state and attachment to the Joker completely override her rationality.

During Akham Asylum

While Batman and the security guards escorted the Joker through the Intensive Treatment Center of Arkham Asylum, Harley was already in the security control room waiting for his signal. As the Joker broke free, she opened the adjacent security field which allowed him to escape Batman and implemented his takeover of Arkham Asylum. Per the plan, Harley began releasing their thugs from all levels of the Asylum. Harley then took Warden Sharp hostage, took possession of his decorative cane as well as wore his Warden Identification Card, and contacted Batman on the monitor. She claimed that the Joker was now in charge of the island and that she was substituting for Sharp as Warden. She also told Batman that Joker was having a homecoming party with Batman as the guest of honor. Batman gave Harley one chance to surrender, which she refused before she smashed her monitor with Sharp's cane, which cut off the feed.

When Batman made his way to the elevator shaft in Secure Transit, Harley appeared, and stated that Joker didn't need to see Batman just yet. Harley proceeded to blow up the elevator cord, which caused the elevator to crash to the floor below and sent herself to the top, and nearly killed a security guard named Henry Smith had Batman not saved him. Harley then regrouped with Frank Boles, who had taken Commissioner Gordon hostage. She and Boles proceeded to secure the front entrance of the Intensive Treatment Center and fought off the guards with an army of Blackgate Prisoners. When Joker found out that Batman was tracking Boles via the alcohol in his breath, Harley was ordered to kill him. With this done, she left him behind, strapped to a gurney with a "Dead End" sign on him. Harley, with Gordon, made her way to the Batmobile first, and ordered her goons to break into it. She then proceeded to the Medical Facility, sat in the main entrance with Gordon tied to a bench by her, and relaxing during her "me time."

Batman eventually tracked Gordon to the entrance and found Harley humming to herself, but was unable to reach her due to an electric security gate blocking the entrance. Spotting Batman as he walked in, Harley told him to scram. He asked where Gordon was, to which she replied: "Wouldn't you like to know?." Gordon then shouted to Batman, and Harley told him to shut up and threw a glass mug at him. Gordon called Harley a "crazy bitch," and Joker contacted Harley via monitor. He yelled at her, and she squealed in a startled tone. Joker asked why Batman was at the Medical Facility, as it was "too early." Harley apologized, kissed Joker through the monitor, and asked him not to be angry with her. He then said: "You little minx! I could never stay mad at you!" and turned off the monitor. Harley said that Batman needed to find another way in, bade him farewell, and cartwheeled out of the room.

On the Joker's orders, Harley proceeded to take Gordon to the Experimentation Chamber, where Bane was being held. Harley was ordered to guard Gordon, and kill him if any of the men patrolling the room spotted Batman. To buy time to set this up, Scarecrow was released to distract Batman. Harley taunted Gordon, telling him that once he and Batman were dead, the Joker would marry her. However, things didn't go as planned; Batman evaded being seen and knocked out Harley by crashing through the ceiling.

Left alone, Harley woke while Batman was busy fighting off a Titan- powered Bane. She promptly escaped back outside. Harley recorded a message for one of the Joker's fake patient sessions with Batman at the Visitor Center, taunting and insulting the Dark Knight. Following her orders, Harley returned to where she had left Sharp, for more of the Joker's insanity. As Batman managed to save Dr. Young from Zsasz, Harley was sent to deal with them; she remained unaware that the Joker had booby-trapped the safe with the Asylum's codes. By the time she arrived, Young was dead from the blast and Batman was out-cold. As Batman woke, Harley joked that Young deserved her death as Joker hated "squealers."

Harley removed the tape on Sharp's mouth, allowing him to insult her. She smacked him with his own cane in return, breaking the jewel off of it. Amused, she tells Batman that "that old looney thinks he runs this place," taking Sharp away for more torture.

Harley left four goons to take Batman to 'the party', but he defeated them and used the Warden's DNA traces from his severed cane tip to follow her. Harley then made her way to the Penitentiary with the Warden, and forced him to read a variety of threatening statements written by Joker over Arkham Asylum's intercom system and tortured him when he hesitated and insulted her.

Harley lead Batman on a goose chase in the Penitentiary. In the Decontamination Room, Harley had two guards strung up and ready to be gassed with Smilex. However, Batman freed them both and got them out of the room before the gas could go off. Eventually, she manged to trick Batman into the Security Control Room, where she had locked up Sharp. Batman saw Harley on a nearby monitor, passing by Poison Ivy's cell. Despite not being on 'Joker's Party List', Ivy convinced Harley to let her free since they were friends. As Ivy happily strode away and blew Harley a kiss, Harley sighed and said: "She's a good kid."

Batman followed Harley and surpassed a variety of her traps until there were a few goons left standing. Harley even electrified the pacification system on the asylum floor to the maximum power to stop his advance, and electrocuted a security guard as a demonstration. Harley then flips up to the vent and taunted Batman and said “Won’t be easy trying to catch me” and blew him a kiss and ran away. Batman eventually got past this obstacle and fought his way through the remaining Blackgate Prisoners and escaped Arkham Lunatics before the fifteen remaining thugs attacked Batman in Extreme Incarceration.

After they were defeated, Joker decided that Harley had failed him, and removed her from the 'party list', much to her annoyance. Out of anger, Harley exited the room and used her acrobatic skills to attack Batman, but was simply thrown aside. Batman then took Harley's 'party list' and Harley tried to punch him. But Batman flipped Harley over, scanned her hand, and acquired her fingerprints. Batman then proceeded to lock up Harley in an adjacent cell, and she accidentally revealed the Joker's location at the Botanical Gardens and claimed that he would rescue her. Batman left Harley crying alone in her cell, getting nothing but insults.