Harley Quinn (Batman: Arkham City)

An Arkham Asylum psychiatrist assigned to treat the Joker, Dr. Harleen Quinzel instead became obsessively fixated on her patient, believing herself to be in love with him. She helped him escape confinement and took on her own criminal identity as Harley Quinn. She remained at the Joker's side during his painful recovery from the effects of Titan.

Batman: Arkham Asylum

 * See: Harley Quinn (Batman: Arkham Asylum)

After Arkham
Six Month's later, Harley has been incarcerated in a high security cell, believing the rampant rumors that the Joker is dying to be false. However her hopes are soon shattered when she overhears a conversation between some guards not only confirming the Joker's short lifespan but also a conspiracy to have him killed. With this she kills and replaces one of the guards planning to kill Joker and rescues him right in the middle of the attempt on his life.

With this she hijacks a supply boat and uses it to sneak into the recently completed Arkham City, setting up her and Joker's base of operations in a abandoned factory. According to Hugo Strange, Joker's inevitable fate is having a hard impact on her causing her to fall into a depression and adopting a increasing millitant approach. Later on she is shown helping Joker with his recruitment campaign screening a potential recruit Lester Kurtz, giving him his clown mask, and showing him to his room before he ran off.

Batman: Arkham City
"It would be a shame to get blood all over my nice new outfit. What do you think, Bat-brain, like it? What am I saying? Of course you do! Who wouldn't?"

- Harley during her first encounter with Batman

Harley Quinn has taken over many of the duties of leading the Joker's gang due to his illness and is more vicious and deadly than previously because of her anger regarding the Joker's health. Harley even supervised the kidnapping of Nora Fries, wife of Mr. Freeze. Shortly after Batman rescues Catwoman from Two-Face, Harley launches an attack on the Arkham City Medical Center and kidnaps one of the doctors, taking her to Joker's Funland in the old Sionis Industries compound, and also implies that the last doctor got executed for failure to find a cure. When Batman comes for her, Harley is watching over the doctor she kidnapped nearly be executed by Mr. Hammer for failure, until she declares a change of plans and has them execute the medic via the roller coaster. When Batman revealed himself and defeated her gang, she scolds Batman and later disappears into Joker's private office, sealing it behind her, although she also encounters Clayface-Joker and briefly mistakes him for the actual Joker before realizing her mistake, causing Joker to hush her. When Batman arrives, Harley is crying over the dead body of the Joker only to reveal that it was a trap and attacks Batman alongside Joker.

With Batman infected with the same poison that is killing Joker, Harley keeps an eye on the Dark Knight as he tries to save Mr. Freeze from Penguin. After his rescue and the creation of a cure, Harley steals it and returns it to the Joker. The Joker, feeling revitalized, starts acting like his old self again and resumes his love hate relationship with Harley. While pursuing Joker to retrieve the cure, Batman finds Harley tied up outside of Joker's office. Batman leaves her and continues after Joker. In actuality, she wasn't able to deliver the cure to the Joker, as Talia al Ghul had intercepted her and stolen it, as well as tying her up outside Joker's office before she could get the chance to deliver it.

Harley was present outside the Monarch Theatre as Batman carried the lifeless body of the Joker out of it and out of Arkham City. She gasped and dropped to her knees sobbing uncontrollably at the sight. It is implied by guards that she has taken over Joker's operations; nonetheless, her position is tenuous as many believe she would not last without the Joker's support and many members voice desires to defect from the gang or usurp her (some gang members even voice plans to rape her, implying her life is in greater danger then she realizes).

Arkham City Profile: Dr. Hugo Strange
Harleen Quinzel

A.K.A Harley Quinn

The Joker's plaything and sometimes girlfriend, Harley Quinn was happy to leave Arkham Asylum so long as she could be with her 'puddin.' Her devotion to the Joker is admirable, but it is clear that his illness has laid a heavy burden on her as well. Her behavior has become evermore erratic and vicious, as she appears to be in a state of emotional metamorphosis, manifested by her change in wardrobe to a more militant, harsh appearance.

Dr. Hugo Strange: Side Note

Ms. Quinn’s behavior has become evermore erratic and vicious.

~ Dr. Hugo Strange

Trivia

 * In one of the Arkham City preorder commercials for GameStop, Harley is the narrator.
 * If the player goes into Harley's office in the Sionis Steel Mill, they will see a pregnancy test next to her old outfit from Arkham Asylum. If they zoom in, it will show that the test is postive. Also, if the player finds this before the game ends, Harley will sing a version of "Hush Little Baby", suggesting that the baby has already been born, though it is not known how much time has passed between the game's events and her singing, since she couldn't do anything but cry over the Joker's death for quite some time.
 * If the player listens in to some of the Joker's minions outside the church, one of the minions, when the other asks whether the rumors are true, will ask whether he meant rumors about Harley Quinn being a trans-sexual. Also, the same goons will mention that they heard that Harley Quinn either married Joker, or he dumped her months ago.
 * Through out the Steel Mill there are little statues of Harley holding a glowing ballon. If the player uses this they can hear her speak a message meant for Joker's thugs; however, the player is meant to destroy these as part of a Riddler challenge. If any remain following Joker's death they play a recording of Harley crying.
 * If defeated by Joker's thugs Harley's message will occasionly play instead of Joker's, and will be the only ones to play after Joker's death.
 * Rumors are spreading that there are possible fathers of Harley's baby. One is the Joker, since they are a couple no matter what. Another is Hush, due to her singing Hush Little Baby, and his hideout having a baby cradle. Lastly, Clayface is seen as a a possibility, as Harley couldn't tell a difference of both Jokers for a while. We could see a blond baby, a green haired baby, a dark haired baby, or a morphing baby.

Game Over Lines
thumb|right|300px|Harley Quinn's game over screens.
 * "Stupid little dead bat! Who's gonna save ya now?"
 * "I knew it. You're nothin' but a lightweight loser."
 * "You were supposed ta save Mr. J bat-brain."
 * "If you're dead, who's gonna save poor Mr. J?"
 * "Neh-neh-neh-neh-neh-neh."

Gallery

 * Harley Quinn (Batman: Arkham City)/Gallery