Hi guys! Thanks for all the reviews, follows and favs! XD

It seemed I wasn't clear enough in the last chapter. Yes, Rin was reborn as Harry's sister, not fem-Harry. She's one year older than Harry. Huzzah, big sis!

As for her short hair...I tried Googling to see if there's any one-year-old baby girl with long hair, but I can't find any. So, yes, she had short hair for now because she wasn't old enough to grow her hair long.

And sorry, I just noticed that Ron's birthday is on 1 March 1980, so I made a mistake in the previous chapter. For the sake of this fic, I'll change his birthday to sometime in April 1980 (not 1 April...apparently that's Fred and George's birthdays lol).

Well then, enjoy!

Disclaimer: I do not own Harry Potter or Nasuverse.

Warning: Rin-centric (needed some intro for her), corrupting babies and cuteness-overload.

Tohsaka Rin, now named Anna Potter, felt as if her world had turned upside down.

She thought she'd known all the risks of studying Kaleidoscope under the Wizard Marshall. Zelretch always joked about meeting her other versions from some parallel worlds (the weirdest one was her being a magical girl) and about her being a part of a certain threesome. It was infuriating and completely embarrassing whenever her mentor spew out these ridiculous information, especially when Shirou or Luvia were around.

But because of this Rin had always assumed that 'parallel worlds' meant worlds that shared similar foundation with similar rules. Magecraft had always been a constant, and so do all the rules revolving around its theory and the organisations involving its practice. Zelretch could easily hop around different worlds and still retained his recognition of being a Dead Apostle Ancestor and the Second Magic practitioner (and an overpowered prankster, apparently) because each world that he'd visited more or less had a similar system to her world.

Not this one, though. It was either her mentor hadn't bother to mention the existence of this world, or Zelretch had never been to this world before. This world, in which she'd been reincarnated into, was totally alien to her, in a way that made no sense at all.

.

.

.

A black dog came into her room.

Rin peered at the animal, wondering how did it managed to come here. Rin was not aware that they had a pet, because in the past four months since her (re-)birth, there was no indication that they had one.

Then, a rat entered her room.

Rin scrunched up her nose in disgust. Ugh, she didn't expect their home to house a rat's nest -

A stag followed.

Since when is their house a zoo?!

At least, the last one to enter was a human - specifically one of her father's best friends, Remus Lupin. They (yes, they, as in the dog, the rat, the stag and the human) lined up in front of her crib, standing proudly as they faced her.

Then, they...bowed, and began tap-dancing.

Rin didn't know if these quartet were expecting her to clap happily and sing with them or something, but apparently they didn't expect her to start frothing.

The merry band of tap-dancer were alarmed by the bubble coming out of her mouth. The stag galloped/scrambled towards her and transformed into her father -

She fainted.

.

.

.

"Hey, ickle Anna," James cooed at her as he seated her on the baby mat. Behind him, one of her self-appointed uncles, Sirius Black, took out a broom and grinned mischievously. Rin idly noted her mother was suspiciously absent. "As my daughter and heir to the Potter, you are obliged to master this one important technique Uncle Paddy is about to demonstrate."

Rin wanted to say why it was Sirius who'd demonstrate to her a family technique - surely it was supposed to be closely guarded and Potters-only - but eight-months-old Anna tilted her head cutely instead and asked, "Aah?"

"You'll see, you'll see," Sirius said, then continued in a lower voice, "Better to corrupt you now when your mother isn't around to stop us."

Then, he mounted the broom, and shot off into the sky.

Damn, Rin thought, I so want that.

.

.

.

It was the first time her parents brought her out of their house to interact with other magi, er, magical people.

They traveled using the Floo Network - a very unpleasant and totally inconceivable but stupidly common way of teleportation in the Wizarding world - to The Burrow. Apparently, it was the family home of the Weasley family, and one of the temporary secret meeting places of the Order of the Phoenix. The Order was created to oppose the rise of a Dark Lord named Voldemort (and why, why a Dark Lord would name themselves that) and Rin's current family, the Potters, was one of its members.

Rin could only gleam so much from eavesdropping her parents' conversation, but the Dark Lord problem appeared to be a serious concern to her family. She loved her current family, maybe even more than the Tohsakas, and she was determined to help her family out as soon as possible. She didn't want to lose her parents and her sibling again, especially her younger brother who was still inside her mother's womb.

But being a baby meant it was not that convenient to bring her around whenever there was an Order meeting. Sure, she was not as difficult to handle as any normal babies, but the fact still remained that someone needed to watch over baby Anna all the time. Besides, bringing a baby into a room where violent arguments between members could begin anytime was a bad idea, and Anna was prone to fainting for no reason, as Lily had argued.

James looked sheepish when she said that.

Thus, one of Rin's parents would usually stayed at home to take care of her, while the other went to attend the meeting. That lasted for about a year, until Rin finally grew desperate for information regarding the Wizarding War (and, well, she was bored) that she utilised her puppy-eyes skill to convince her parents to bring her along.

"Well," Lily sighed exasperatedly as she saw her husband crumble into dust upon receiving the cuteness-overload deathblow delivered by her daughter, "I guess we could bring Anna along. I heard the Weasleys have a lot of kids around, anyway."

A lot, indeed.

Rin's eyes twitched upon seeing the number of children the Weasleys had had. There was Bill, the oldest, followed by Charlie, Percy and apparently another two sets of twins. That was already seven children, and Molly Weasley, the matriarch, was now eight-months pregnant.

And they were all redheads. It seemed red hair was such a dominant trait in the Weasley family that all of its members had red hair of similar shade. She idly wondered if Shirou's family also had a trait like this before he was orphaned by the Great Fuyuki Fire.

Then again, Archer had white hair. She had theorised that it could be due to overuse of magecraft over the years, but it could also be a genetic trait -

A sharp cry echoed from upstairs, breaking her out of her musing. Molly, in all her pregnant glory, could still dash upstairs very quickly, and soon the others followed with their wands out, except for James who was still carrying Rin.

They reached a room in the second floor, where an old man was viciously glared at by an irritated Molly, and a twin redhead babies crying their eyes out. The old man (gods, she itched to shave the damn beard) claimed he didn't do anything, prompting Rin to roll her eyes.

At least, the twins' sobs had died down when they'd all arrived. They looked up at the crowd, and one of the twins brightened up upon seeing her.

Rin sighed. Damn, it seemed she'd gained her first fanboy in this world.

Said fanboy began to stand shakily on his stubby legs and reached up towards her direction, but his father scooped him and his twin up before the boy could do anything else.

"James, come with me," Arthur Weasley said as they all descended back into the dining room. "And bring your baby girl with you! I've just recently bought a playpen for Danny and Jo, since they always wandered into the kitchen. Ickle Anna could make some new friends!"

James agreed, and moved to put his daughter in the playpen. But Rin's tiny grip on him tightened, and she unleashed a fearsome pout.

Bring me with you to the meeting, her pout seemed to convey, because that was the main reason why she wanted to follow her parents here. Rin stole a glance at the babies in the playpen - one of whom was already crawling towards her - and turned back to add some tears and wobbly lips to her pout.

James wavered at the relentless attack, but Lily slapped his arm and gave him a pointed look. He took a deep breath and painfully looked at his daughter, who widened her eyes in betrayal as he slowly pried her grip on him open.

Father, no!

Alas, her traitorous father left her, alone and miserable in a playpen filled with babies, one of whom was a dreaded fanboy.

"Jammit," she grumbled, and closed her eyes in resignation. Rin sighed, and turned to glare at the boy -

"Lin!"

Rin blinked, before frowning. She must have heard wrong -

"Lin!" the fanboy cried, as he stumbled around before finally stopping in front of her. His eyes were locked on her as he pat his chest and said, "'s me, Chiyou!"

Chiyou…? What -

A toy sword materialised in the boy's hand.

It all clicked.

"Sch-Ch-Chiyou?!" Rin spluttered, struggling to say his name with her baby mouth. The boy - Shirou - nodded eagerly, letting the toy dissipate. Rin tackled him in a hug, making them both fall onto the baby mat - and despite the awkward position, Rin felt relieved for the first time since she was reborn.

Shirou laughed and patted her back. They stayed like that for a minute, before Rin rolled over and sat in front of him. She looked at him up and down, noting that he was reborn with red hair again, though this time his eyes were blue. And now that she knew he wasn't a fanboy, she realised he looked so damn cute as a baby.

As she scrutinised him, he did the same to her, staring at her short hair for a bit longer. Rin noticed and blushed, shyly tugging her own hair. She felt Shirou softly pat her head, and when she looked up at him, he beamed at her.

Rin wanted to cover her face with her tiny palms and let out a long "D'awwwww", but instinct kicked in. She looked sideways and grumbled instead, in a 'tsundere' manner that was familiar. Shirou chuckled at her cute antics.

Though, as she turned, she caught a glimpse of another redhead baby at the corner of the playpen, sitting on the mat and covering his face with both of his hands. Rin blinked. Oh, she forgot the other boy, apparently Shirou's twin…

"…"

She waddled slowly towards the other boy. Shirou noticed this, and desperately tried to stop her. But he tripped over his own feet and fell hopelessly onto the mat.

The other boy peeked through his chubby fingers, and warbled something like "Pug" upon noticing her over his shoulder.

"Ooh?" Rin began, grinning in amusement. The boy turned back to facepalm, while Shirou sighed in resignation. "Woo's dis?"

Cue a mad (baby) cackle.

.

.

.

"Voldemort's targeting the Bones now, and I heard his next move might be this weekend."

"Then, we should ambush them -"

"MWAHAHAHAHHAHAHHAHA - "

All the Order members jumped at the unexpected high-pitched laughter. Heads turned to look at the general direction where the baby playpen was.

"..."

"..."

"...Blimey, for some reason that laughter reminds me of you when you were about to prank someone, James."

"Who, me?"

Edit - zoo, on 7/12/2018. Thanks, Knightowl 4183!