On the night of the kyuubi attack, a girl named Rose was born. She, along with her twin brother, Naruto were used to seal the beast. The Yondame highly doubted that any newborn, even an Uzumaki (known for their strong life forces) could hold it. He split it in two less dangerous parts. The Yin, already predisposed to femininity, was held within his daughter. The only reason they were both needed for the process was the babies' young ages. At the announcement of what the village's beloved Hokage had died for, the children were doomed to an unkind first impression and unkind treatment, regardless of the secrecy of the reason.
In another world, the still alive leader watched his son born for the second time, to a different mother. Although his job would keep him far away and his child a secret, Iemitsu knew that Nana, kind loving woman she was, would provide a loving parent here, in his other, regardless of what happened at the village he was no longer leader of. He would allow himself a while before he started erasing his family's tracks and mourning the mother of his daughter. After all, even if his Kushina lived on this other, and there was no way of knowing for certain, she could be anywhere. They had both agreed to live happy lives with families in both their others, hardly uncommon, but he truly missed her already.
Unknown to him, on the other side of the same world his other's wife, Lilly, as she was called here, was birthing her daughter a second time, and having a much easier time now. Rose was delivered in a hospital, not some random cave, she had a mediwitch to help with the birth, and her husband James and his friends were all properly worrying about her instead of blankly watching as she died from complications in childbirth. Lilly was content with the wonderful world that she still had. As she had said to her love, James, "So what if there was some prophesy threatening the life of our daughter, or a war that we're fighting in. We have friends, we have support, and I will be grateful for all I can, even in trying times." Now she was going to raise her darling daughter along with an obviously loving husband. She was going to make the most of this wonderful life, and her wonderful daughter.
In the twins other, life was going bad, but it was better than it could have gone. Even though the matron of the orphanage disliked them, their other's parents loved them as much as they could. Even though the first years were rough for Naruto, he always had his mother to fall back on when the other's jeers were too much. Nana wouldn't abandon her son for the world! Even though his father got too upset at the implied neglect that his village distributed against his orders to interact with the boy half the time, and too busy trying to drown his memories of Kushina in alcohol or fend off his job the other half, he still was a steady presence and the first to say that the village's actions were wrong and scare off thoughts of being unloved. His sister was not so fortunate.
"Lilly, take Rose and run, I'll hold him off!" Rose's luck had run out, Lilly knew that much. Kushina had had a good carrier as a shinobi and a daughter that was everything she had dreamed of. The prophesy she had initially dismissed as not that big of a deal was killing James and about to kill her baby too. She refused to let her daughter die here, even if she would be losing more than her daughter could. Shaking her head, she bravely faced her future murderer. "Not Rose, please take me instead!" "Stand aside, girl" "No" with surrender removed from her options, the shinobi inside her had Lily activate as many of the defenses as she could. Of course, no one who had experienced as many battles as she had would be stupid enough to leave her base undefended. Chains interspersed with fire spells or any wider ranged combat spells tried to kill the enemy before he could get her. It was all in vain, as the rune-based fire was frozen, chains were slashed and she - gone in one spell.
The killing curse worked by trapping someone in their other. When a person didn't have that to go back to, it couldn't correctly function, but the curse had to do something! It tried to trap something into something else so that it could still complete its purpose, distorted as the effect was. It might have trapped an animal's heartbeat in its brain, killing the animal and eventually the beating to (brains aren't supposed to pulse). It could have trapped Lilly's head in her stomach, or something equally gruesome. This time, it chose to contain Lilly's urge to protect her child in the pattern in her daughter's core instincts. Lilly, regardless of the vitality of her Uzumaki heritage or the adjustment of having contained the kyuubi, did not survive the shock of the transfer. When he tried to destroy his prophesied enemy, Rose's instincts with all the power of the kyubi contained within her managed to put together the girl's first accidental magic. Voldemort was trapped in his horcruxses by the rederected spell, and the wizarding world was saved.
Rose's life took a turn for the worse without her mother. The matron of the orphanage's dislike soured to loathing, as the jinchuriki brat started to wake everyone in the orphanage with dreadful nightmares every naptime. Even worse, the Yammono that she had taken the initiative to call to check if the girl was alright had strait out refused to deal with the Jinchuriki because, "Entering the mind of a jinkchuriki is a good way to get eaten by their byui, lady" Even if it was true, the matron thought there was no reason to make her feel stupid like that. "Those brats wouldn't be staying here long" she murmured, looking forward to the time she could enroll them in the ninja academy and leave those two with only a stipend from her instead. She didn't like those particular brats either way, and she was not going to put up with that awful noise disturbing the rest of the children if she could avoid it. Let the people in the child's other deal with the trauma that they were most likely the one to cause. She would not suffer the indignity of being questioned on that child's behalf twice!
In the world where Rose had just been orphaned after surviving the attack that killed her parents, she was unfortunately abandoned at her maternal aunt's house, regardless of her mother's will having a number of other homes that could better accommodate a magical child. Rose's aunt, happy in her home with the same love in both others and the same son, was beyond unprepared to raise her half-sister's child. At a loss for how to raise a child she only had partial access to, she ended up mostly leaving the child's emotional needs in her husband's care. She didn't want to waste her effort only to have it ruined by other influences or make another child suffer through being molded into two opposite things the way that she was subjected to, the most she did Rose was to give her a few sleep medications for the nightmares. There was nothing else that Petunia thought to do.
Petunia's husband wasn't much better. Raised in a strict household that did not tolerate disobedience, Vernon (in both worlds) was a stern control freak who had no clue of how to directly nurture anything, much less comfort a nightmare! Confusion and paranoid worry turned to irritation and neglect when sister, a sensible woman both too strict and too intimidating to raise more than pet dogs in her household, suggested that he leave training to children that he could enforce it on. Vernon knew that the smallest bedroom could make a fair child's room, regardless of where the child came from. That was where the child would sleep, and she could have Dudley's almost outgrown crib and wear his outgrown clothes. Vernon believed that his wife could handle anything more complex or mundane than that. It seemed to work for his son. Of more importance, "Why didn't you tell me you had a sister?", his wife had a secret that she had to answer for.
Having Naruto as her brother was Rose's only solace in those unloved first years. He, while not as disliked, didn't manage to make lasting friends in the orphanage (he still was baffled when over the top goofiness didn't make him friends, especially as it worked on his mother!). Rose, not hating or overtly annoyed at him (due more to half understood instincts than any tolerance for his antics), loved him more than anyone else there, and she was the one to scare off at least half of the potential friends! She wasn't very likable with her screams or, to a lesser extent, with her frightening stories, especially once she managed to learn how to talk and read the stories from the library. Still, she had managed to prove that her friendship was worthwhile when she comforted and listened to him after his father, oh so stern but loving and well loved, went off to "become a star", whatever that was supposed to mean. He didn't fully understand, mostly because Naruto was only four at the time. It was nice and felt good to have someone paying attention to him, trying to care for him, especially after his mother fell into a depression over losing his father's presence to some faraway place that the postcards said was Italy. "It seems like she lives for his daily calls sometimes!" he would complain to his sister. It was in Naruto's first remembered trial that the siblings really connected and started to love each other dearly. It was far better for them both to have a friend instead of just an occasional kind word or action, especially from a rival for attention. Naruto decided that he would love and care for her, just like his mother said he should. The siblings cuddled together, did the best they could at learning to read and write together, and pulled pranks together.
As her chores assigned by her Aunt began, Rose asked her brother for help in learning how to do them. Even though Naruto wasn't interested in learning to look after the house, his mother, saddened by his father's absence to his far-off work, was thrilled to have her son take an interest in something they could share. Rose managed to get a basic explanation of what to do from her brother, and combined with what she could read about the subject, she managed to complete meals, gardening, and cleaning wonderfully- to another culture's standards! Rose's Aunt was frightened by her niece's ability to do things that she hadn't been taught, to Petunia's knowledge. The daily reminder that her niece had an other that Petunia couldn't control unnerved her to the point of violence on a few terrified days. Her husband wasn't pleased by the child's treatment, and Petunia's increasing worry upset him. The feelings of all members of the household ended building of each either in a negative spiral. Rose wanted to be loved and productive, so she learned everything that she needed in her other. Petunia was frightened by her niece's "mysterious abilities" and treated the child critically as possible, holding her to impossible standards. Vernon was upset at both of their behavior and occasionally lost his temper at them. Dudley, noticing that he got less scrutiny as Rose got more, began staging 'accidents' for her, and those motivated Rose to both do better and form a rivalry with her cousin, teasing him and trying to outdo or outmaneuver him. This kept Petunia terrified, Vernon violent, Dudley teasing, and Rose both frustrated and happily contrary. With less and less comfort in her Aunt's house, Rose focused more and more on productivity, keeping herself ahead of the game. Living in such conditions in one world, it was no wonder that her identity and opinions were developed almost entirely in her other during those early years.
When the twins turned five, they entered the academy from an apartment of their own, by the choice of the matron, who was allowed to kick children in the academy out as long as she gave them the necessary stipend, checked that they didn't starve once a week for the first year, and didn't separate siblings in the process. The twins were together as they tried to make sense of budgets and schoolwork (Rose actually thrived at the academics and figures). With his awesome sister's help, Naruto didn't sink into debt or stupidity. When they were given congratulations on their entrance into the academy by the Hokage himself, he was the one she hid behind. Naruto was proud at the implied trust that he could protect her, even if the Hokage was less enthusiastic at her fear. Pranks that he had started during their years as rivals were remade into a team effort. They were something that the children enjoyed between schoolwork and expectations. This was when they grew to a larger scale, both for targets and attempts. Those missions were a good bonding activity for the twins. With the added challenge presented by some neglect from teachers, however, mundane pranks that started to bore Rose became more infrequent. Rose now preferred to break into the library (the person at the desk wouldn't let her get a library card) to get books on their assignments or on interesting topics. The agreement that she could emphasize capability and he could still do some solo pranks did end up calming the last of their rivalry, along with the promise and proof that their team pranks were still the best remembered.
When they took an early examination to move up to gein after their first year in the academy, the divide between the siblings tried to reform. Naruto had put more effort into making friends than work and simply wasn't naturally smart as sister. His chakera control, not aided by countless control exercises in both worlds, was horrible, and with that deficiency on top of his oversized reserves, there was no way he could pass his ninjutsu portion. Without that, he had no way to pass with his poor written work (caused partially by his lack of attention during class), and no hands-on coaching in taljitsu, he failed the exam on all three subjects, averaging to a disappointing, but entirely expected, order for Naruto to return to the class next year. With all her studying and supplemental reading, Rose somehow managed to pass. This wasn't nearly as well expected or received. The Sadame had noted that keeping children in the academy longer tended to leave them less unstable and didn't do anything to fight Naruto's early flop at the academy. With Rose passing, entirely unexpected with the level of sabotage she put up with, there was a much higher chance that she would end up somehow weird. He hoped that it didn't affect Naruto, the bright boy was already like a grandson for the aging Hokage.
With only six years to get over the Kyuubi, Rose's sensei was much less accommodating to Rose than she had hoped for. Even the Uchiha prodigy couldn't put the girl in her place, and it was embarrassing for all involved when someone with no formal training who no one, but her twin, liked did just as well as a boy with every advantage. Unnerved by her excellence, young age, and the Kyuubi within her, he tried to move Rose into a less threatening niche. With the contrary capability that was quickly becoming normal for her, Rose pushed herself to perfection in the infiltration training she was given. When there was a well-trained boy two years older than her so obviously there, that's who everyone compared Rose's progress to. Jealousy mingled with hate as the Uchira clan thought that Rose was so capable because of private lessons under the kyuubi (honestly, the only thing that of the kyuubi gave her was ridicules chakera & magic levels, disregarding her canines and slightly rougher tongue!) and hated her for it, spreading rumors. They most certainly disliked the person making their heir seem mediocre, and did their best to get back at Rose for it.
Naruto stood his sisters successes better than anyone else. By now, he had learned to rely on her, and being better than him was just something that he expected from his sister. Rose was willing to share what she knew with him the way that he had taught her, so Naruto didn't find anything off about the lessons. He was going to take care of his sister, and anyone who doubted was just lying.
The first day of school was frightening to Rose Potter, but it was put to shame by her entrance into ANBU. She had been mortified when she didn't recognize her name without Uzamaki presiding it and her cousin loudly her who the teacher was calling, but it was dwarfed by the embarrassment of forgetting her mask name at lineup. Not recognizing which letter the teacher was pointing to made her feel foolish, but not as foolish as doing a stance wrong before an instructor. Her cousin's public taunting was hurtful, but being expected to participate in spreading nasty rumors about herself was worse. Faced with such cruelty, Rose started to search for friendships in the world with only Dudley stopping them, not the whole village!