Harley Quinn (Batman: Assault on Arkham)

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.

Batman: Arkham Origins/Batman: Arkham Origins Blackgate
Main article: Harleen Quinzel (Batman: Arkham Origins)

Batman: Assault on Arkham
She was a frequent member of the Suicide Squad tasked by Amanda Waller. At some point, Harley Quinn and The Joker, during one of the latter's infamous crime sprees, proceeded to set a vehicle containing various contraband that was to be sold by the Penguin on fire, which caused the crime lord to hate the duo even further than before. During one of their crimes, Joker proceeded to kick Harley Quinn out of their escape vehicle while it was still moving, apparently causing severe enough injuries to leave her with bruises. This resulted in Harley Quinn breaking up with the Joker, and trying to disassociate herself with her ties to him.

Shortly before being recruited by the Suicide Squad again, Harley Quinn underwent a group therapy session, and attempted to watch on her tablet an episode of the Looney Toons show. However, the head therapist tried to take it away from her, which resulted in Harley Quinn literally biting the therapist's ear off to get it back, also continuing to watch it.

Afterwards, she awoke at the Suicide Squad headquarters, also lamenting her having to undergo a mission again, alongside her fellow members Deadshot and Captain Boomerang, as well as new-comers Black Spider, KGBeast, King Shark, and Killer Frost. She then was briefed on the situation by Amanda Waller, with KGBeast being killed when he unwisely challenged her claim that they were installed with a tracker that would explode if they went against mission protocol. She was the first to agree to the mission to break into Arkham Asylum. Afterwards, she and the others were knocked out and then came to onboard a transport plane over Gotham, with her also expressing impressment at Black Spider (a vigilante who hunts and kills criminals) getting out of his seat and threatening Captain Boomerang, claiming that ninjas were awesome. She was also the only one who was actually enjoyed the freefall, laughing her heart out when they were falling to Gotham City, and also surviving falling on her head. Later, she managed to strike up a destructive relationship with Deadshot, and later met with Penguin. However, the meeting nearly ended in disaster when Penguin recognized her among the Suicide Squad and tried to gun her down in a rage, still sore over Joker's earlier actions and her involvement in it. She also expressed minor annoyance at Deadshot offering to kill her when he tried to talk Penguin out of it. As part of the plan, she was dropped off at a toy shop so she could cause enough vandalization under the pretense of trying to search for a doll to lure Batman over to get her into Arkham as a prisoner. However, during the exchange, Batman proceeded to interrogate her about the location of Joker's dirty bomb that he hid somewhere inside Gotham, which neither she nor her Suicide Squad was even aware of. Batman then had her arrested after determining she genuinely didn't know, but was still suspicious as he found her to have given up too easily. She later was escorted by a "guard" (actually Deadshot in disguise) through Arkham over to the Junction box, although they nearly hit a snag in the plan when it was revealed that Joker was being kept in the isolation cell. Harley Quinn then tried to attack him in revenge, with Deadshot trying to stop her to avoid blowing their cover. Ultimately she managed to stop, although not before humiliating Joker by shooting her gun through the airholes of the otherwise bulletproof prison. This also resulted in Joker having an easy escape attempt. However, a gas explosion ended up placing Arkham Asylum on yellow alert, which resulted in Batman's involvement becoming likely, although they attempted to stall him by including old security footage in an attempt to "trick" him into thinking everything was normal. Later, she proceeded to distract a guard by undressing and luring him over to be taken out by King Shark upon regrouping with the group. Eventually, they got into evidence lockup at the Asylum, with her eventually finding her mallet that she misplaced. However, she ended up having to fight Batman with the others, due to Batman not being fooled by the swapped tapes. She was the only one to be suspicious of Black Spider supposedly beating Batman. Eventually, at the prison yard, Harley Quinn and the others proceeded to fight several guards, due to King Shark not being subtle in his actions. Eventually, she was subjected to electroshock therapy by the Riddler to undo the trackers on their necks, with her taking amusement in the pain, although the electroshock therapy failed to short out King Shark's device due to his skin being too tough. Batman was also exposed to have been posing as Black Spider (confirming Quinn's suspicions), although she got subjected to electrocution again by Riddler by accident due to Batman throwing a batarang into his arm. She was later saved by Deadshot and evacuated with the rest of the Suicide Squad after Joker burst in. She later returned to Joker and claimed to have manipulated everything to ensure Joker escaped (although it was implied that she was only going back to him in an attempt to save Deadshot from being killed by the Joker). After Deadshot outsmarted the Joker, the latter escaped through the laundry chute with Harley, with Joker proceeding to activate the dirty bomb inside Harley's hammer after knocking her out.

She later reappeared on the helicopter with Joker where the latter proceeded to threaten Deadshot. She hesitated to pull the trigger when picking up Joker's gun, although she was forced to break off from shooting either of them to regain control of the unmanned chopper (due to Joker and Deadshot getting into a fight), causing her to pilot the chopper very dangerously due to not being experienced with piloting it (with Joker even remarking on it by telling Deadshot "You know she's going to kill us, right?"). To make matters worse for her, Batman also arrived on her tail in the Batwing, and was eventually forced to utilize everything she had in a failed attempt to dissuade the caped crusader's pursuit. She was then forced out the chopper by Batman into an office building while the chopper, with Deadshot and Joker still in it, crashed into the area two floors above the same building. Harley Quinn then ended up fighting Batman in a frenzy, being sick and tired of his actions against her, as Batman's trying to warn her about the bomb in her mallet. However, she was knocked out by him, with Batman proceeding to disarm the bomb just as Joker is defeated by Deadshot and trapped inside the chopper to fall down into the street. Presumably, Harley Quinn ended up locked up at Arkham Asylum for real afterwards.

Batman: Arkham Asylum
Main article: Harley Quinn (Batman: Arkham Asylum)

Batman: Arkham City
Main article: Harley Quinn (Batman: Arkham City)

Batman: Arkham Knight
Main article: Harley Quinn (Batman: Arkham Knight)

Trivia

 * Harley Quinn's romance with Deadshot was based on the romance between their New 52 versions.
 * Harley Quinn's shoplifting of the toy store was similar to Catwoman's first crime act in Batman Returns.