They're best friends, "girlfriends," partners in crime. They have mutual respect for one another, in part because they're intellectual equals (well, almost). There's love there, its exact nature undefined, and it can shift from day to day. And at times, there's something more there – in a look, a touch, when the rigid one bends, when the silly one gets serious.

Harley dances, bounces around the truth. Ivy mostly ignores it so she can retain her composure.

Except tonight.

It would never work. It should never have gone this far. She should have been more careful.

Dr. Pamela Isley stared out the window of some penthouse, which she'd coaxed with no resistance from some nameless piece of meat. She was better known as supervillain Poison Ivy, but the doctor was certainly in tonight. Her PhD brain was working overtime as she indulged her tendency to overanalyze.

"What's up, doc?"

Ivy allowed herself a small smile before turning to face the very subject of her overanalysis, who was shaking the snow from her pigtails as she burst through the door.

(Harley burst through everything. Doors, hearts, life.)

"That joke never gets old," said Ivy, turning to face her.

"You pretend not to like it, but we both know it always gets a smile," said Harley. She kicked her boots against the floor, then slipped them off and padded over to Ivy in her sock feet.

She was going to hug Ivy, but Ivy turned back to face the window, and Harley quickly hid her disappointment and stood beside her, facing out. Harley was used to these pensive moods of Ivy's and usually didn't mind.

They were quiet for a minute. Maybe 5 seconds. But either way, Harley couldn't take the silence anymore, and she bumped Ivy's hip with her own.

"Hey."

Ivy looked at her sideways, again with that little half-smile. "Hey."

"Seriously, what's up?" Harley asked. "Did something happen at work today?" Ivy was a staff scientist at S.T.A.R Labs and tended to be obsessive about her work, sometimes staying at the lab overnight.

Ivy shook her head. "No…I've just been thinking."

Harley put her hand to her forehead, walked away, and pretended to faint onto the couch. "Good grief, Red! How many times have I told you: thinking is the worst way to spend a Friday night?"

Ivy's smile widened. "And just how would you recommend I spend my Friday night?"

Harley leaned up on her elbows. "Now you're talking! I have a few ideas." She wiggled her eyebrows at Ivy suggestively. Ivy walked over to the couch, leaned over the arm…and threw a pillow at Harley, who let out an "Oof!" and fell backwards off the couch.

"Got you, Harl!" said Ivy, enjoying her small victory – at least, until a leg swept her feet out from under her and she went down in a tangle of green limbs, laughing.

Harley rolled over on top of Ivy and held her shoulders down. "No – I got you."

Suddenly, Ivy felt the pressure of Harley's hips on hers. And Harley became aware of how close her face was to Ivy's. An errant drop of melted snow rolled down Harley's pigtail and splashed on the carpet next to Ivy's ear.

They stopped laughing at the same time.

Harley swallowed hard and said, "So…what were you thinking about, again?" She was faintly surprised when her voice came out an octave lower than usual.

Ivy reached up to brush a renegade strand of hair behind Harley's ear. Her hand trailed down Harley's cheek to her jaw, and her thumb brushed gently across her lower lip. She stared into Harley's eyes for a long moment, and then said "Pretty much this."

Harley hardly dared to breathe. She knew Ivy sometimes got spooked when they were playing like this, but this time it didn't feel like playing.

Slowly, slowly, never moving her eyes from Ivy's, Harley lowered her lips to the dark green lips below her, until finally they touched in a gentle kiss. Ivy still had her hand alongside Harley's face, and now she trailed it downward, then slid it around to cup the back of Harley's neck, deepening the kiss.

Harley moaned against Ivy's full lips. She tangled a hand in Ivy's hair and sucked gently on her bottom lip. Then it was Ivy's turn to moan as she felt Harley's teeth scrape over her lip lightly.

Suddenly, Harley pulled back, surprising both of them. She groaned and rolled off to the side, then propped herself up on one elbow and looked at Ivy. "I'm going to hate myself for asking this – but what are we doing, Red?"

Ivy turned her head to the side and regarded her coolly – well, as coolly as she could under the circumstances, with flushed cheeks and tangled hair and her breathing still slightly off-kilter. "I was under the impression that this was part of our whole…thing. Are you really going to act like this has never happened before?"

Harley sighed and sat up, leaning against the couch. "I know…I can't believe I stopped us either. But you just looked like you were thinking so hard before, and you said it was about – well, this – and it got me thinking, and you know I can't stand that, and so please please tell me what you were thinking about so I can relax!"

Ivy chuckled, a low, throaty sound that never failed to send a shiver down Harley's spine. She sat up facing Harley, kneeling in front of her, and trailed long, green fingers up and down her forearm as she spoke. "Harley…I was thinking about how this all started between us – and, to be honest, about why it shouldn't work." When Harley's face fell, Ivy put a finger under her chin and tilted her head up so that blue eyes met green. "Please let me finish. You know that on paper, this – us – makes no sense."

Ivy shook her head when Harley's lower lip began to quiver. "Wait! I'm not explaining this well. I didn't expect you to stop kissing me, and I didn't think we'd have to talk about this tonight." She released Harley's chin and considered for a moment, tilting her head to one side. "Okay, let's make a game of it. I'll start. You'll catch on."

Harley brightened a bit at that. "Well played, Red. You know I can't resist a good game."

Ivy said, "The game is called 'Opposites.' Here goes: I can't stand company – except for yours, and my plants. You can't stand to be alone."

Harley said, "Okay…I'm rubber and you're glue." Ivy shot her a look. "Fine. I'm always the first to laugh at the joke. You…don't really joke."

"That's good," said Ivy. "You see where I'm going with this. Let's see: I'm less human every day. If not for you, I'd be almost entirely plant by now. You, on the other hand, are the most human person I've ever known."

"I'm not sure whether to be offended by that," said Harley. "But here's one. I play the fool. You don't suffer fools."

Ivy considered for a moment, then looked resigned. "I use people. You…have been used."

"Yeah, but not by you, Red!" said Harley. "This is getting kinda heavy. Let's see, I'm black and red, mayhem and fire. You're green – but not with envy!"

Ivy grinned at her. "Cute. But see what I mean? It's not logical at all." She sobered. "The last one I thought of: I'm cold but never cruel – not to you, at least." Her voice got even quieter. "You were only cruel to me…once." Their eyes met, and the weight of that sunk in. Harley took Ivy's hand, and Ivy brightened slightly, enough to continue. "Yet here we are. So earlier, I started reflecting on how we got here. That's why I was lost in thought when you got home."

Harley considered her friend for a minute. Then she hopped up onto the couch and patted the cushion next to her. Ivy joined her and they grinned shyly at one another. Harley settled into Ivy's shoulder naturally, and Ivy slid an arm around her shoulders just as easily.

"So tell me a story, Red. Tell me what it was like for you when we met, became friends…everything since then."

Ivy leaned over and pressed her lips to Harley's hair, a small smile on her face. "Okay, sweet pea. Where to begin…"

It starts innocently enough, and slowly. Ivy actively avoids human contact, and while Harley can't stand to be alone, she doesn't exactly have a history of mutually supportive relationships.

Yet there's a connection there, a spark. And they're instantly drawn to one another, closer and closer, despite the occasional interruption, be it an Amazonian excursion or a psychopathic ex.

Next chapter: Arkham!