Bella felt her bra snap a few seconds after putting it in. Like she feared it was getting too small for her. It was shrinking because there wasn't enough magic in it.
Bella took a band new bra out of its packaging and lifted it in front of her. With a wave of her finger a mystical blue magic flew out of her palm and into the bra. The bra was covered in and surrounded by glowing blue runes, before a flash of blue light showed her that it was fully enchanted. As she put it on the bra grew and shrunk until it reached the perfect size, not so big that her tits sagged but not so small that it felt tight.
Bella was a homunculus: a special being completely created by magic. She wouldn't need to eat or sleep if consistently supplied with magic, but as a result every surface of her body would slowly leak magic as a result. Extended contact with her bare skin had the ability to break anything down to dust, so to prevent her clothes from crumbling by just wearing them she had to enchant them with a special spell.
Magic was an incredible thing. As she got ready to go to magic school she could see brooms sweeping the house and dishes washing all by themselves. All she had to do to get to campus was sprinkle a blue dust on the floor and walk down into the portal it created. It was an incredible sight, but as a homunculus she had to be much more careful with it than others. When two sources of magic get close they have the chance to fuse together and run out of control, and when you're made of magic something like that could be life threatening.
Bella didn't let that stop her however. The tall and busty blonde wanted to be a wizard, and wasn't going to let anything stop her goal. A requirement for majoring in wizardry was Magical History class, and as she had a seat she was reminded of the person she hated the most: a busty redhead by the name of Beni. Upon seeing each other the two groaned and looked away, the sight of each other having ruined each other's day.
In a way Beni and Bella (also known by their production names of ฿€Ŋɨ225 and ฿€ŁŁæ563 respectively) were like twins, being created by the same person on the exact same day. That could explain why the two look so similar, having minor differences between them like hair color and the position of the freckles on their cheeks. They've been compared their entire lives, and they hated it.
That wasn't why they hated each other though. Bella always thought Beni was trying to copy her, and Beni felt the same. Maybe it was just the way their creator made them, but the similarities between the two was astounding. The two had the same likes, same aspirations, even used the exact same techniques when spell casting, and they found that annoying. Both deemed the other as a mere copycat, and being next to each other would just make it easier for one to copy the other.
Class started, and the lecturer talked about historical magical alchemists like John Draneerich, who discovered and coined the Draneerich Effect. They all knew what it was, the fact that the more similarly two spells are crafted the more likely they are to merge when put next to each other, but Beni and Bella were still going to write notes about it. They placed their textbooks up next to them to block each other's view of their notebook, and made sure to enchant them to make sure the other couldn't use a spell to look through. If a copycat was going to try and copy her, she wasn't going to make it easy. The books found themselves slowly drawn to each other though, being pulled towards each other by this same effect.
BANG! The teacher was shocked by a sudden blue flash coming from Bella and Beni's seats, bringing the attention of the entire class. Beni and Bellas were just as shocked, wishing they could just crumble into a ball and die from embarrassment.
"The two of you aren't messing with magic in the middle of class are you?" The lecturer looked right at the two "twins", who were blushing and shuffling in their seats.
"No sir."
"We would never sir."
"Good." The lecturer went back to teaching the class, while Beni and Bella glared at each other for the rest of the class.
Once the class ended and everyone headed out for their next classes the only two remaining were Beni and Bella. They held onto separate ends of the same textbook, refusing to let go while they glared at each other with the wrath of intense magical beasts.
"Let me guess," Beni said. "You did that in order to see what I was doing and copy me even more?"
"One thing," Bella said. "If anyone caused that and tried to copy the other, it would definitely be you!"
"Don't joke around! We both know that you've been copying me since we were first created!" Beni tugged on the textbook.
"Stop lying to yourself! You have been copying me, not the other way around!" Bella tugged on the textbook.
A side effect of the Draneerich Effect when it came to enchanted objects was that it could completely fuse two objects together. The more similar the objects were the more likely they were to completely fuse when their enchantments did, and this was what happened to the textbooks. This would potentially mean that one of them would have to get a new textbook, but with textbooks being so expensive neither wanted to be that person.
"Stop copying me," Beni said, pulling on the book, not noticing the edge of her shirt begin to perk up as if it was getting pulled. "And give me my book back!"
"You're the one who copied my enchantment," Bella said as she tugged, not noticing the edge of her shirt also appearing to get tugged. "So it's mine!"
"You copied me!"
"No, you did!"
"Give it back!"
"It's mine!"
Suddenly the two found themselves getting pulled towards each other, their shirts practically leaping for each other. Having been enchanted with the same enchantments the shirts were equally as affected by the Draneerich Effect as the textbooks, the two being pulled towards each other at top speed until colliding in a flash of blue light. Beni and Bella tried to turn away before they could make impact, but it didn't slow their collision in the slightest.
While enchanted items usually fuse completely under the Draneerich Effect, inability for them to be lined up properly and slight interruptions during the fusion process can lead to only partial fusions. This is what happened to their shirts, which looked similar to one big shirt but actually had four sleeves instead of two. The designs on the front were on both sides of this fused shirt, and Bella and Beni were snugged inside back to back.
"FORGET IT! I'M GETTING A NEW ONE!" The textbook was dropped to the ground as the two practically gave up, having gotten each other to their boiling points at this point. The combined shirt was pulled off and the two stomped in separate directions, only to find themselves snagged to each other.
Two items that had pressed into each other and started to undergo this effect were the brand new white bras the two had enchanted that day. The straps were starting to fuse into each other, with now connected bras pulling their wearers back as if they were attempting to absorb each other.
"Was stealing my book AND my shirt not enough for you!? I can't believe you!" Bella pulled forward, tugging on Beni's bra. Beni immediately felt the effect, feeling the cups start to press into her large breasts and push them back.
"You do all this and STILL pretend that it's my fault!? Listen to yourself for once!" Beni pulled forward, practically yanking Bella's bra. Bella gasped as she immediately felt the effects, the cups now pushing down and squeezing her large breasts.
"At least give me back my bra!"
"It's my bra that's in jeopardy here!"
The two angrily pulled forward, wanting their absolute most to snap each other's side of what was essentially now one bra and walk away as far as possible. The individual bras were still fusing into each other though, pulling the two closer together just as much as the two tried to pull each other apart. The cups pressed harder and harder into their breasts, digging into flesh and pressing down on their nipples. It was like every step forward was them groping their hands down on the other's breasts, making the two feel rather excited.
Their bras weren't the only things they gave the same enchantments to. They were too busy stepping forward to notice but the tips of their panties also started to tug as if they were attracted to each other. Slowly and slowly they pulled towards each other, until the tips finally met and with a flash of blue light they started to fuse into each other.
Bella noticed something dig into her pussy, and was shocked when she realized what it truly was.
Beni felt that her panties seemed a bit tighter than usual, and gasped when she saw the answer.
"My bra AND my panties!?" Beni was furious.
"One piece of underwear wasn't enough!?" Bella was enraged.
"YOU BITCH!"
The two pulled and pulled and pulled, groaning and straining in their attempt to take their enchanted breasts away from their twin. The cups of the bra pressed down into their breasts, squeezing them harder and harder as if their actual hands were assaulting them. Their panties dug high into each other's groins, rubbing into their pussies in a harsh mutual wedgie. The arousal between them was starting to grow, becoming more and more distracting the more they pulled.
"Let go of my underwear already!" Bella pulled with all her might.
"You need to let go you freak!" Beni pulled with all her might.
"LET GO!" The two pulled with all their strength but their legs started to quiver. The arousal had started to build up too much and the two found themselves with a surprise orgasm. The rush of pleasure was incredible, immaculate they'd say, but that rush distracted them and made them unable to pull at full strength for a second.
That second was enough for the Draneerich Effect to take full effect. The force fusing their underwear together pulled at an incredible force, yanking both bodies towards each other with incredible speed. Once their bodies made contact there was the sound of cracks and a flash of blue light, and the two passed out.
Bella woke up a few hours later, on her side in a dark empty classroom. She still seemed to have her bra and panties on which was nice, although they seemed a bit tighter than usual. And oddly she didn't feel Beni on her back at all, so maybe she had left and realized who was copying who. She hoped that was the case at least. She looked down at her bra, thankful it wasn't stolen.
"Ow ow ow ow!" She heard Beni's voice behind her, seemingly in pain. "Don't pull on my neck like that!"
Before Bella could realize what she meant her neck suddenly bent backwards. It was like someone had grabbed her by her hair and yanked her head back against her will. "Ow ow ow ow! Let go already!"
Homunculi like them were made of magic, and as such equally susceptible to the Draneerich Effect. Usually the way their bodies are encased would prevent any magic from escaping and fusing with similar magic, but the impact from their bodies slamming together broke such a barrier and allowed the two to fuse together as well.
The two were completely fused to each other back to back, the two almost looked like one girl with her reflection behind her. A move forward for one would be a move backwards for the other, and it was infuriating to no end.
At the very least there was no risk of being copied anymore.