This is very dark. The M rating is there for good reason.
Harley wandered around the abandoned Arkham Asylum, lost in thought. She had helped the Joker capture Robin and now her Puddin' was in the process of showing Robin how much fun he could have if he joined their family. Harley had wanted to start a family with the Joker for years and while she would have preferred to start by having a child of her own, adoption was still a pretty exciting.
It's not adoption, it's kidnapping.
Harley squashed that thought swiftly. It wasn't like they could have just gone to an orphanage and filed for adoption. They had unfortunately built up such an ugly reputation that nobody in their right minds would hand over their kids to them. But Harley could be a good mother! All she needed was a chance and Puddin' had finally given her that chance.
Although she had to admit, the screaming was a little unsettling.
Harley arrived outside the area that she and the Joker were using as their apartment. Sometimes, she wished the Asylum was still inhabited so she could escape from the boredom. She wished Red was here. Unfortunately, her best friend had disappeared and Harley had no way of contacting her. Maybe Red had finally given up on her. Harley knew she hated the Joker but she just couldn't see what a charming, lovable rogue he was. Even if he was a bit temperamental.
Harley was distracted by a particularly loud scream from Robin and instinctively winced. From the volume! Just the volume. Boy, that kid had a set of lungs on him. The Joker stepped out of his laboratory.
"Hi Puddin," Harley chirped, "How's it goin'?"
"He's a stubborn kid," the Joker replied with that charming grin that she loved so much, "You still sure you wanna be a parent, Harl?"
"Yep," Harley replied confidently.
"Well, you can start by giving him some supper. Just don't overfeed him. We don't want the lad getting fat, do we?" the Joker patted Harley's stomach, smirking. She glanced down at her belly, insecurity bubbling up inside her. Was Puddin' saying he thought she was fat? She stopped worrying about it when he kissed her cheek and squeaked gleefully before skipping into the lab.
Robin was strapped to a table which was sitting upright. He was sweaty and exhausted but looked up and scowled at Harley as she bounded towards him.
"Hiya," Harley said, "Settling in okay?"
"Brilliantly," Robin said sarcastically.
"Mista J asked me to whip up some supper," Harley said, "I should warn you though, I ain't much of a cook."
When she finished cooking and started feeding Robin, practicing for when she would start spoon-feeding his future little brother or sister, Robin immediately spat the food out in her face.
"Hey!" Harley shrieked, wiping her face and the stains on her outfit.
"You're right, you really aren't much of a cook," Robin said snidely.
"You, ungrateful little brat," Harley shrieked. Robin didn't even flinch when she slapped him. He just looked at her with a slight smirk on his face.
"Must feel good to be the one hitting instead of being hit for once," he said casually.
"Fine, you can go hungry," Harley snapped, throwing down her spoon and storming out.
Over the next couple of weeks, Harley occasionally went on quick trips into Gotham to get supplies for the Joker. She wasn't entirely sure why he needed them or what he was planning but if he was happy, she was happy so she didn't question him. Once a day, she would feed Robin who had reluctantly started to accept her admittedly less than stellar cooking. Puddin' had often said she needed to work on that.
Occasionally, Harley thought about how uncomfortable it must be to spend three weeks strapped to a table.
"AAAARRGH!" Tim Drake screamed as electricity blasted through his body. The pain was unbearable and he was sure the drugs in his system were somehow making it even worse. He couldn't even hear the Joker's cackling over his own screams, "STOP! PLEASE! I'LL TELL YOU ANYTHING! ANYTHING!"
Finally, the Joker stopped and leaned close, leering at him maliciously.
"What information could you possibly have that I would want?" the madman asked.
"The…" Tim took a breath, "The identity of Batman." Aside from raising his left eyebrow, the Joker's expression didn't change.
"Go on," he said, straightening up. Tim hesitated. The Joker put his hand on the lever that activated the electric shocks.
I'm sorry, dad.
"Bruce Wayne," Tim choked out, "Bruce Wayne is Batman."
The Joker looked at him for a moment, silently processing the information. Then he shrugged.
"I could have worked that out years ago," he said, "If I'd actually wanted to." He grinned, pulled the lever and Tim started screaming again.
Nearly three weeks after the kidnapping, Harley went to give Robin his daily meal. She entered the lab and blinked in surprise when she saw the kid. His skin was bleached white and his hair was green. Aside from still wearing his Robin suit, which was torn and filthy by now, he looked like a smaller version of the Joker.
When he looked at her, Harley saw a look in his eyes that she hadn't seen before. Until now, Robin had always looked at Harley defiantly whenever she entered the room. His eyes had a burning strength and determination in them which many, including Harley, would find admirable, especially in one so young. But over the last few weeks, that fiery determination had dimmed and now it was gone entirely. Instead, he started begging.
"Please," Robin moaned, "I can't… I can't take it anymore, Harley. Please just… make him stop."
"He has stopped, sweetie," Harley said cheerfully, squashing the flicker of pity that started welling up inside her, "By the way, lovin' your new look."
"What did he do to me?" Robin whimpered. Harley picked up a mirror and showed him. Robin stared at his reflection for a long moment, "No, no, no, no, no, no! Not like him! Please, not like him!"
"Relax sweetie," Harley tried to sooth him but Robin started thrashing on the table.
"Kill me!" he screamed, "Please! I'd rather die than be like him! Please, kill me!"
Nobody had ever asked Harley to kill them before. She wasn't sure how to respond to the plea so she just watched as he strained against his bonds, biting her lip uncertainly. Robin exhausted himself swiftly and stared at her with tears running down his face. This wasn't a joke. He was staring at her with such sincerity that she knew he would welcome death right now.
"Please," he begged pitifully and for the first time, Harley realized how young he truly was, "If you have any humanity left in you, please just kill me."
"Aw, you don't wanna take after your old man, kiddo?" asked the Joker as he emerged from the shadows. Harley jumped and Robin stiffened, "You hurt my feelings. Not as much as I'll hurt yours though."
"No, no!" Robin screamed, "Stop him, Harley! Please, I'm begging you! Stop him!"
Harley wasn't sure what to do. She had seen people beg before and been responsible for their begging a fair few times but this was different. This was a little boy. Doubt and guilt clawed at Harley's mind. She wanted a family but this… this was nothing like what she had envisioned.
Then Robin started screaming in agony and for the first time, Harley witnessed the Joker torturing him with her own eyes. Until now, the Joker had always kept her out of the lab when he was disciplining the boy, saying that she wouldn't understand why such harsh methods were necessary. Now Harley watched Robin writhe on the table, electricity blasting through his body, his screams echoing around the room and mingling with the Joker's maniacal laughter.
It reminded her of the times the Joker had "disciplined" her. Except he had never resorted to this. He had beaten and cut her many times but he had never strapped her to a table for three weeks, injected god knows what into her veins, or electrocuted her.
Harleen Quinzel would have been appalled at what the Joker was doing right now.
Harley Quinn was struggling to fight back the same feeling. She didn't realize she was silently crying until the screaming stopped and the Joker turned to her.
"That's how you discipline a kid, Pumpkin Pie," he said with a "charming" smile. He stepped towards her, "What's wrong? You look a little upset. You want me to kiss your boo boo better?"
"N-no Puddin'," Harley said, hastily wiping her eyes, "I'm fine. Just a little shocked, that's all."
"Hah, hah, hah!" Joker cackled, "That's a good one! Now give him his supper and get out!"
Harley sneaked back into the lab while the Joker was asleep. Robin was still strapped to the table, whimpering, and moaning in his sleep. Harley looked at the knife in her hand, then raised it, aiming for his heart. The kid had suffered enough; he deserved a quick, clean death.
A hand grabbed her wrist. Harley froze and turned to the Joker who shook his head disapprovingly.
"Now, now Poo, what kind of mother tries to murder their own child?" the Joker asked, twisting Harley's wrist, causing her to gasp in pain and drop the knife.
"P-Puddin', I just…" Harley began. The Joker backhanded her and she fell against the table, waking Robin in the process.
"You should know by now, that you never do things without my permission," Joker hissed, "Looks like you need some disciplining too." His glare morphed into a grin, "And I can give our kid a grownup lesson in the process."
He grabbed Harley by her nightshirt and hurled her into another table, spilling the serums he had used to transform Robin all over the place. Harley felt pieces of glass cut into her back but when she tried to scream the Joker slammed his lips onto hers with bruising force.
Robin watched in horror as the Joker raped Harley right in front of his eyes.
Harley was used to having painful sex with the Joker. He was always rough but this time, he was doing everything he could to make it as painful as possible. He pressed her hard against the table, driving shattered glass deeper into her skin, then he reached out and grabbed a larger piece of glass. He drove it between Harley's breasts and pulling it down, splitting the skin between her boobs. It was a shallow wound which looked more serious than it really was but it still hurt like hell. Once the glass was below her breasts, the Joker slid it to the side, curling it beneath her left breast while Harley shrieked in agony. Then he placed the glass back between her breasts and curled it in the other direction. It now looked like Harley had a cat's lips curling under her breasts in a smile.
The Joker looked at the bloody cat's smile in Harley's body, smiled, then tossed the glass away and slammed into her at full force, drawing another scream from her lips.
Robin still couldn't look away.
Finally, the Joker was finished. He nibbled Harley's left ear while she lay sobbing beneath him.
"You'd better get cleaned up, Poo," he whispered, then stood up. Harley stumbled to her feet, her naked, bloody body on full display to the little boy, who stared at her with horrified fascination.
Then Robin started chuckling.
Harley and the Joker looked at him as Robin's shoulders shook with laugher, which became louder and louder as he stared at the bloody smile on Harley's body.
Harley wiped her eyes and glanced at her still bleeding wound, then at Robin. He was laughing at her but in the same way the Joker laughed at her. She was making her little boy happy. Harley started smiling crazily as Robin's laugh grew so loud that it echoed around the chamber.
Then the Joker and Harley started laughing too.
I just can't see Harley, at least not the one from The Animated Series, being comfortable with torturing a little kid for three weeks. In Batman Beyond: Return of the Joker, she never showed any sign that she was upset about what the Joker did but she still got rehabilitated and appeared briefly at the end of the film, so there must have been some part of her that realized the Joker was going too far.