Disclaimer: I do not own the rights "Batman" or any of its character, nor do I own any rights to the comics or the films. I own nothing save for any original characters I have created.

A/N: This was inspired by a prompt I received on Tumblr from if***nglovebatman. The premise is Scarecrow and Poison Ivy breaking into the same lab, and due to pressing needs deciding put aside their differences and "share" the lab.

Chemistry

Jonathan Crane clenched his jaw as a thick, serpentine vine slithered across the back of his hand. Its leaves rustled against his skin, leaving behind a scratching sensation that he found both unpleasant and repulsive, and he suppressed a shudder of disgust as he swatted the vine away. It recoiled from him as if it were stung by the action, and Crane could feel Poison Ivy's eyes boring into him from across the laboratory.

"Don't you dare hurt my babies, Jonathan," she warned. "I'll only play nice if you do."

"I beg your pardon, Miss Isley," Crane replied through gritted teeth, "but I would hardly consider your vegetation contaminating my work area to be playing nice."

The offending vine encircled itself around Ivy's green wrist, traveling up her arm with fluid grace before settling across her shoulders. Cradling its head in her hand, Crane watched with morbid fascination as Ivy leaned down and planted a gentle, motherly kiss onto the stem; the vine seemed to flourish underneath her lips, reciprocating her affection by running a tendril across her cheek.

When Crane had approached the guard booth at Wayne Chemicals and found it unoccupied, he'd thought it was a stroke of luck in his favor. After discovering the laboratory doors already pried open, he realized that someone else had the same intentions as him—to break into the lab. But who? Run-of-the-mill hoodlums looking for ingredients to the trash that flooded Gotham's streets? Two-Face searching for explosive chemicals? Or—and the thought was enough to make Crane pause in his tracks—Joker whipping up another batch of his laughing gas? The possibility of coming face-to-face with Joker filled Crane with dread; he imagined that the clown would think it was particularly funny to make a man who tortured others with fear die from laughter.

But while he had felt somewhat relieved to find Poison Ivy in the lab, the corpse of the hapless security guard wrapped in the snaking vines beside her, he'd still approached her cautiously and with a vial of fear toxin clasped firmly in his hand. Ivy may not have been a menacing, unpredictable clown, but she was equally dangerous.

"Miss Isley," Crane had said with all the charm he could muster (which, admittedly, was not an impressive amount), "you're looking as fetching as ever."

"Flattery will get you nowhere, Jonathan," Ivy replied, "except perhaps into mulch."

Crane narrowed his eyes. "Well, in that case, let's get right to business: what are you doing here?"

"I could ask you the same question."

Crane let out a sigh of exasperation. "To be quite frank, I don't actually care why you are here, Miss Isley, I just care that you are. I need to use this laboratory and you are interfering with my plans."

Ivy scoffed. "And how is that my problem?"

Crane contemplated dousing Ivy with the fear toxin, but he was unsure if her biology would react to the compound. Physically overpowering her was out of the question; her plants were powerful enough to snap a Gotham Rogues linebacker in half, much less a slender man such as himself. No, if he was going to get what he wanted it would only be by appealing to her.

"How about a bargain? If you let me use the laboratory undisturbed, then I'll let you have half of the fear toxin that I create."

Ivy paused for a moment, then nodded in agreement. "You'll have to forgive me if I don't shake your hand," she said coolly.

"Of course," Crane replied, and forced his lips to turn upwards into a small, agreeable grin. He had absolutely no intention of sharing his toxin with Ivy upon its completion, but he was confident that he would produce enough to incapacitate or at least momentarily stun her and allow him time to escape, plant-like body chemistry be damned.

It had proven to be more difficult than he anticipated, not least of all due to the constant interruptions and distractions Ivy's plants caused. But after a few hours his task was complete, and he held in his hands four small vials containing enough toxin to plunge Gotham into nightmares twice over.

"I'll be taking that," Ivy whispered into his ear, and before Crane could react Ivy leaned forward and pressed her lips to his.

Anger and humiliation washed over Crane as he felt his body betray him, rooting him to the spot as his lips responded to Ivy's kiss. His grip on the vials relaxed, slipping from his grasp and into Ivy's open palm. He cursed himself inwardly for his lack of foresight; he should have known, should have seen it coming from a mile away. Stupid stupid stupid.

And yet another part of him was deliciously intoxicated as his mind grew hazy, drunk on the softness of her lips and the dark green iris of her eyes and the light fragrance of the flowers woven through her hair. That part of him welcomed her embrace and let out a moan of disappointed yearning when she broke their kiss, smiling as she waved her fingers at him while she walked out the laboratory doors, leaving him alone with his swimming brain.

He'd make her pay for this. He would not rest until he'd found her and crushed every single one of her stupid plants underneath his foot before doing the same to her. He would ruin her if it was the last thing he ever did.

Maybe he'd just wait a while and see if she came back first. He'd forgive her then.

But only if she kissed him.