"If..." Dan had to clear his throat before he could speak. "If you turn her into anything but a girl, I'll have to turn into a girl?"
"Yes, Dan, I'm sorry," Mom said, though she didn't sound very sorry. In fact, she sounded downright gleeful. "The bloodline must continue, and that means a daughter."
"I'll accept that on two conditions," Dan said, and ticked the first one off on his finger. "One: I want to be good looking. If I have to face life as a girl, I don't want men judging me badly because I'm homely. Okay?"
"Okay," Mom said.
"What?" Kat shrieked. "You can't really be planning to do this, can you?"
"I absolutely can," Mom said. "You abused your powers, so now they'll be turned against you. Now shut up, you've squandered the privilege to argue."
Kat's head drooped. She looked defeated.
"Now don't misunderstand me," Dan said. "I don't want to be some artificially enhanced Barbie doll. But moderate breasts, good figure, smooth skin. I want to be a girl who boys will notice."
"Done. Your second condition?"
"Turn Kat into a dress I can wear. Something nice I can wear out in public. Something pretty."
The more Dan talked, the paler Kat's skin got. Her jaw flopped open, and her hands began to shake.
"Done," Mom said again. "I'll make her a pretty dress. And just so we don't have to buy you a whole new wardrobe, I'll make you the same size as your sister. She has nice clothes." Mom turned to Kat and jabbed her wand at her daughter, who still stood silent in the face of her impending doom. "And let me make this perfectly clear, young woman: you will be aware of everything that happens while you're a dress. You and Dan will be telepathically linked, so you can communicate, but you will be completely powerless and at his mercy. Do you understand that?"
Kat tried to speak, but only squeaked. She nodded.
"Good." Mom pointed her wand at Dan. "Now get ready, because this will be uncomfortable."
Dan felt his skin ripple beneath his clothes, then suddenly the room started to move upward. No, not the room: he was getting shorter, down to Kat's height. His heart pounded as his skeleton reshaped itself, and he felt a sucking between his legs as his penis vanished up into his pelvis, leaving him with a vagina. He felt the muscles in his thighs change from strong to shapely, and his hair spilled down his back in long, dark curls. His t-shirt strained as breasts pushed it outward, and a round ass filled out his jeans. Most of his clothes hung too loose on him, and his jeans started to fall down, though his breasts stretched his t-shirt out of shape.
Across the room, Dan saw himself—herself—in Kat's full-length mirror. Despite the ill-fitting boy's clothes, she realized, she was quite the babe. She'd be quite the hit at school.
Mom lowered her wand to look at her work. "That looks nice. You're very pretty, young lady, and I'm sure you'll make me proud to call you my daughter. Would you like your new name to be Danielle?"
Dan smiled. "Dani for short," she agreed.
"Absolutely." Mom smiled widely, showing all her perfect white teeth. Clearly she was proud of what she'd done to her former son. "Everyone outside this family will think you've always been a pretty young lady named Dani."
Then the smile faded, and she turned on Kat. "Now then, young lady," she said. "You will stay this way until Dani asks me to change you two back or until she comes of age and gets her powers, whichever comes first." She jabbed her wand out, and as a streak of light poured out, Mom sighed sadly. "Remember you brought this on yourself."
Kat threw her hands up, but she couldn't block the spell. She rippled in her clothes, like she was surrounded by heat shimmer, and then suddenly a heap of empty clothing dropped on the floor where Kat had stood a moment ago. Sticking her wand in her belt, Mom crossed to the pile, reached in, and tossed Kat's jeans and blouse on the bed. The Kat-dress was still caught in her bra and panties, but Mom pulled them off and tossed them aside as casually as an old shoe.
"There we are," Mom said proudly, holding the dress up. "Won't you look pretty in this!" Mom turned to Dani and showed her new daughter the Kat-dress.
Dani smiled to see that her mother had turned her petty, spiteful sister into a...