After lunch, Danielle decided to hit the bathroom before her next class. She wasn't especially pleased when Kat followed her, but her now-twin sister just stood in front of the mirror, apparently touching up her makeup or something - Danielle didn't know. At least they were the only ones in there - that meant nobody to tease them.
When she'd finished her business, Danielle exited the stall to see Kat standing there, a wicked grin on her face. She gasped and looked for an exit, but Kat was positioned directly between her and the door. There was nobody here and nowhere to run.
"I'm not losing this easily, Danny," Kat smirked. She opened her hand to reveal a small stone, like a rainbow-colored pearl. "If you'd been born a girl, if you'd had the same witch training Mom gave me, you'd know what this is. It's a caster battery, infused with magical energy. I don't have to be eighteen to tap into existing energy - I already know how!"
Danielle began to tremble. "But...but...what are...?"
Kat's sneer intensified. "I can't make Mom lift her spell on me, but I'm damn well not gonna let you go unpunished for tattling. We'll see how you like being a full rabbit until Mom changes me back!" She gestured at Danielle, who felt a surge of magical energy.
Danielle expected panic to set in as the world began tomgrow around her, but all she felt was a growing knot in her stomach. She wondered how much worse everything could get when suddenly Kat let out a yelp. Danielle looked at her sister and gasped - Kat was shrinking too!
"No!" she shrieked. "Mom used a mirror-magic spell!? I should've been able to tell! No, no, no! I don't want to be a rabbit!!!"
Much to her horror, Danielle felt a prickling sensation all over her skin. She clutched herself, Kat mirroring her actions, as snow-white fur spread across her whole body, making a sharp contrast with her firey red hair. Pink pads formed on the insides of her hands as her fingernails turned into short claws. She could feel her legs changing, her feet becoming slightly more animalistic, altering her stance. Danielle cringed, sure that it was only moments before she was forced down on all fours...
...and it stopped. All of a sudden, it was gone. She didn't know or care why; she was just grateful it was over, for the moment. Danielle turned to the mirror to see what had happened.
Her first shock was the sheer change in size. She had gone from around 4'6" to no more than three feet tall, a mere two-thirds of the size she had been. She could barely see herself in the mirror, and most of what she saw only confirmed what she already knew: she'd gone from being a mostly-human girl with bunny ears and a tail to being an anthropomorphic rabbit-girl.
Surprisingly, though, underneath the fur, her facial structure was basically unchanged - she hadn't developed a muzzle or anything like that. And although she'd shrunk, she was still proportioned like a budding thirteen-year-old girl, just smaller - which would've been a bigger comfort if A. she was supposed to be a girl at all, and B. it didn't imply that this two-thirds size thing was a feature of her new form rather than just a loss in growth.
Kat, now identically transformed, was sputtering angrily and incoherently as Danielle turned to face her. "Stupid...dammit...why can't...should work! Argh! Why can't I-"
She was cut short as Danielle sucker-punched her. Kat didn't fall over, but she was knocked off-balance, and the stone went flying as she tried to keep from falling. She recovered and launched herself at Danielle, who tried to dodge but only got half out of the way. Kat struck her in the shoulder and dragged her brother-turned-sister to the floor with her.
"I have had ENOUGH!" Danielle barked, as the two struggled. "I don't care what you do to me, I'm NOT just going to sit and take this!" She tried to claw at Kat, but her sister grabbed her ear and yanked. Danielle was unused to having such a prominent grab-point, and shrieked more out of surprise than pain. She was about to retaliate when a shout of "GIRLS!!!" interrupted them. Both of them knew what that tone in that voice meant, and they froze in mid-attack.
There, standing by the bathroom door, was their mother. The room around them took on a faintly jittery appearance, like the pause on a cheap VCR - Kat knew this meant their mother had frozen time around them, to avoid interlopers.
"Get off of each other this instant!" she snapped. "I don't care who did what, you both know better than this!" She turned to Kat. "And you, Catherine Louise...I wish I could say I'm surprised, but I'm really not. One taste of power and you go completely ape. I guess there's just too much of your aunt in you."
Danielle looked confused. "We have an aunt?" Her mother sighed, sadly. "I'll explain another time, dear. For now...dear God, what happened here?"
"Kat had a battery stone or something, and she used it to do this!" Danielle said, choking up as she recalled her terror. "She was going to turn me into a full rabbit!"
Her mother slapped a palm to her forehead. "Kat...tell me you didn't use some cheap, street-vendor piece of..."
"I don't see what the big deal is!" Kat snapped. "You took away my power, so I used an enchanter's reserve for power! Duh!"
Their mother groaned. "Dammit, Kat, after everything I taught you about interaction of magics, you go and pull a stunt like that? Did you just forget that enchanter's-reserve stones are imprinted with the spell pattern of the manufacturer, or were you even listening in the first place?"
Kat gasped, and her mother nodded. "Yes, now you understand, don't you? We're going to have to track down the manufacturer of that stone and pray that he's skilled enough to lift this spell without disturbing the spells on either of you." She leaned down close to Kat's face. "And you already might never get your magic back, young lady, but if you've left your brother stuck as a rabbit-girl for the rest of her life, I swear you will be starting over from kindergarten."