Catwoman didn't know a thing about magic.
She just knew certain psychotic clowns shouldn't have anything to do with it.
"WHOO HOO!" Joker shouted, cackling madly. "Oh, believe it or not, kittencat, I'm actually glad you're here!"
The two of them stood before a shining, golden mirror, one which radiated eldritch energy. Catwoman, whip at the ready, glared at him. "Oh? And why's that, nutjob?"
"Because, and I'm just gonna flat out admit this, I'm in love with Batman," Joker said.
Several images came to Catwoman's head. None of them pleasant, and she shuddered.
Joker seemed unoffended. "But he's most definitely in love with you!" he continued. "That's why I brought this! A magical mirror of fusion! It can combine the lives of two whole people, making them one! Altering their backstory accordingly for all involved!"
Catwoman, to her horror, suddenly knew where this was going. "No... NO WAY!" she shouted, turning to run. She wasn't about to become one with the Joker!!
Before she could leap away, though, Joker pulled out a large boxing glove gun and fired it. The boxing glove had a brick in it, which shattered on impact with Catwoman's head, knocking her out. Whistling, Joker picked up Catwoman and walked towards the full-length magical mirror. He patted Catwoman's ample postier. "Well, I can see why Batsy likes you," he conceded, chuckling. "Let's see how I look with it."
Carrying Catwoman, he stepped into the mirror, the two being absorbed by the crystalline surface. There was a bright flash of light, and a luxuriously well-built woman in purple spandex sauntered out of the mirror, green fur cuffs around the gloves and boots. Her top was unzipped, exposing a generous amount of cleavage and bare, pale skin.
The woman's lips were blood red, her short green hair hidden by a cat-shaped cowl. She purred, looking at herself in the mirror... and she remembered.
Sneak-thief Selina Kyle, the Catwoman, early in her career, had been chased into a chemical plant by the Batman. A clumsy mistake on her part had her fall into a vat of acidic chemicals, which bleached her skin white, mutated her hair to a permanent green color, and permanently damaged her brain. On that day, she finally got the joke that was life. A joke she wanted to share with the deliciously sexy Batman. And oh, she could tell he wanted her. If it weren't for those pesky morals, the two would be fucking so hard right now...
Selina Kyle, the Madcat, threw her head back and began to laugh at the glorious comedy of it all...