This is a bit of an AU of my fanfic Life and Death, posted by request - Joker and Harley's twins. This story is not platonic. I might develop this further, later on.

"In the end, it's him and I
He's out his head, I'm out my mind"

When they returned home from the club, she stomped into his room that was more like their shared territory, pulled her shoes off and threw them on his bed for revenge. "Every time I find someone to play with, my family kills him. Every time. He was cute."

"You just wanna be the one giving him the final blow, dear sister. Sorry for stealin' your spotlight."

She glared at him, eyes narrowing. "Don't interfere with my games, J.J. Are you jealous or something?"

"That guy was moving in on my sister, so. Dad would have nailed him to the wall anyhow." He shrugged, picking up her gold-plated hammer from the desk, grinning widely.

"So?" A knife lodged itself in the wall next to him, splintering the wood. He rolled his eyes.

Jaylie held out her hand for her favorite weapon, and when he handed it to her, she used the advantage to pull him close and wrestle him to the ground. He let her win, only for this time. She was funny when she was pissed off, but he didn't want to push her beyond that. Last time she had set his Corvette on fire.

"I'm just practicing! Dad wants to let the Bat live… but we don't. When Gotham is ours, he'll be the first to hang upside down, you know it." He chuckled.

Straddling his chest, she glared down at him. "You need to get some muscles already. You're fourteen."

"So are you." He reached up a hand to pinch her and she slapped it away.

"I'm older than you." She smiled triumphantly.

"By one minute." He huffed at her. "What you lookin' at?" He flipped them around and pinned her against the floor. She bared her teeth, bucking against him as he chuckled. "No muscles, eh?"

She snapped her teeth in the air. "I'll kill you."

"Go ahead and try."

He froze, feeling suddenly self-conscious with their bodies pressed together. She was warm and soft against him, despite her feral expression. He tried to pull back but she caught his wrists in a death grip at the same time, smiling maliciously. "This isn't over."

Their eyes met, the same shade of blue. She looked funnily at him, her grin disappearing, but she wouldn't let go of him. His sister had her moments of complete seriousness, focusing on her schemes, but never like this.

"You're beautiful," she said matter-of-factly. He snorted. "You notice now? Everyone's blinded by me. I'm the handsome jester king."

Dramatically he pulled his hands through his blonde hair, tips dyed red, and she rolled her eyes. Her hair had natural streaks of green ever since their chemical bath, but she wasn't half as obsessive about her hair. He was more vain than his own father.

She let him pull back and she slowly sat up, her eyes never leaving him for a moment. He kept his guard up, prepared for her to pounce the second he looked away. Instead she reached out and wrapped her hands around his head, pulling him closer.

The feeling of self-consciousness returned. He had spent his entire life so close to her, they slept in the same bed as children, they had seen each other naked, but only recently this distance had grown. He'd distracted himself by going out and wreaking havoc on the city, while she preferred ruling from the shadows of the club. Now, there was no hint of her playful aggressiveness, or sign of anger.

They had fought many times and inflicted harm on each other in temper tantrums as well as childish curiosity, but in the end they had each other. It was them against the world. Eventually, Gotham would belong to them. Their parents had prepared them for that, always.

The girl in front of him wasn't the same as the one he used to taunt and play with; she looked differently at him now. Her white-green hair was longer, and his eyes were drawn to her pink lips, they seemed fuller than before. Her body had matured a bit, as well. She seemed less like the wildcat she had been all her life, she was someone else, refined.

In her eyes hinted strange curiosity. Her hands around his head were warm and she looked at him the same way she did at an object she wanted to examine and pry apart, and he prepared himself for her next move, but instead she leaned in and pressed her lips to his.

The touch was soft, yet steady. He gasped against her, tensing up as her hands withdrew, letting him pull away if he wanted. He didn't.

He kissed her back, leaning over her and exploring her mouth. She was completely silent, concentrated, and her hands moved to his shoulders to keep herself steady. He couldn't help himself, running his hands through her hair and pulling her closer.

Her warm tongue darted out to taste his lips, the dried red lipstick, and he felt his entire body reacting to her touch. She leaned in with more strength and he lost his balance when she pushed, toppling over with her on top of him.

When he opened his eyes, he heard her silent gasp as she withdrew, her face just a few inches above his own.

Numbly he stared into her eyes, seeing her usually white face blossoming pink. He tried to catch his breath as he sat up, still intensely aware of her closeness.

"Sorry," she mumbled, not looking regretful at all. The concentrated look on her face didn't waver. A minute passed and they both avoided looking at each other, as he felt his own face heating up. His mind battled his body, trying to push these new thoughts and feeling aside, the feeling of want.

"Jaylie?"

She rose to her feet suddenly, but he grabbed her wrist to stop her. It felt so smooth in his hand. He let his scarred thumb run over the tattooed "JL" on her skin, and she shivered.

"Is this a game?"

She still refused to look at him. "No."

"Then what the hell did just happen?" He stood up as well, refusing to let her go.

His confident sister seemed to have lost all air, all words, until she turned her head and smiled at him. "You liked it, didn't you?" There it was, her most teasing self.

He let her go but she grasped his hand in turn. He wanted to push her away, pissed her with her for always playing with him, but she seemed so serious in the middle of it all. Tilting her head to look at him underneath her bangs, she wrapped her arms around his waist, a common gesture that had been innocent for them just a few weeks earlier.

The sensation of her pressed to him was both pleasurable and uncomfortable – they had both matured into teenagers, and he tried to ignore the way she affected him. He placed his arms around her too, wanting to hold her closer.

He chuckled, letting the sweet, slightly acidic smell of her fill his nostrils. He knew he smelled much the same – she pointed it out from time to time and she always borrowed his shirts when she went to the club with the Joker.

"Well, we ain't getting any more normal, so…"

She smiled carelessly, looking up at him as her fingers played with the golden bracelet on his wrist. "So?"

It was impossible to tell when it all had changed between them, but he realized the flood gates had opened now. Her hand rested on his chest, feeling his heartbeat steadily, and she leaned her forehead against his.

His fingers intertwined with hers, looking so similar, matching rings on their fingers, matching tattoos. Jaylie's eyes never left his. "Like Mom and Dad. Ride or die."

The corners of his mouth twitched, before he leaned in to kiss her again. "You get to tell them."