The likelihood of there ever being more of this is small. So I thought I'd go ahead and post what I've got. It was fun to write.

"Harry Potter."

The hall fell silent as the students and staff of Hogwarts waited with baited breath to see which house the boy-who-lived would be sorted into.

"Gryffindor!" the hat exclaimed, and everyone cheered, the Gryffindor table loudest of all. Harry Potter removed the Sorting Hat from his messy black hair and made his way to the red and gold bedecked table.

"Rose Potter."

The hall fell silent again, this time in shock. Since when were there two Potter children? Wouldn't they have heard if another child had survived that night?

A tiny red-haired girl bounced excitedly out of line and up to the stool. McGonagall stared long enough that the girl looked up at her in confusion before the professor remembered herself and placed the hat on the new student's head.

"Gryffindor!" the hat said after a moment, and the hall broke into whispers almost as loud as the cheers and applause.

"Two Potters." "Both in Gryffindor." "Why haven't we heard about her?"

Some students glanced up at the head table to see what the adults made of the unexpected Potter girl. The staff members looked varying levels of surprised. Most notably, McGonagall looked dumbstruck, Snape looked pained, and Dumbledore looked bewildered.

The girl was mostly oblivious to the commotion she was causing as she made her way to the Gryffindor table and plopped herself down across from the previously sorted Potter.

"Hi!" she said brightly. "So you're a Potter too?"

"Er, yeah," Harry answered, not sure how to deal with the overly-cheerful girl.

"Pleased to meet you!"

She then turned toward the front to watch the rest of the sorting.

"Are you twins?" Hermione Granger asked in a whisper. Rose just shushed her and clapped for Dean Thomas, who had just been sorted into Gryffindor.

"Are you twins?" Hermione tried again as soon as the feast started. "The books didn't say anything about Harry Potter being a twin!"

"Of course not. I don't know why you'd think that – we don't even look anything like each other." Which was true. Harry looked scrawny and underfed, with dark hair and bright green eyes only slightly obscured by his glasses. Rose wasn't scrawny so much as small, with bright red hair, brown eyes, and an overabundance of freckles. "I look more like this Weasley kid than him," Rose added, gesturing to Ron who was currently stuffing his own freckled face with chicken. Then she turned sharply back to Hermione, her eyes narrowed in suspicion. "Wait, what books? What did you do to end up in books?" Rose added, turning to Harry. "No, wait. Never mind," she said as Hermione opened her mouth to list off exactly which books mentioned Harry Potter and in what capacity. "The point is we're not twins. As far as I know we're not related at all. Potter's a very common name, you know."

"Not here in the wizarding world," said an older redhead, dropping into the seat beside Rose and slinging an arm over her shoulders, shoving Ron aside in the process. All of the surrounding first years looked up at him, startled by his sudden interjection into their conversation. Ron mostly just looked irritated that he'd been shifted from in front of his plate.

"Yeah, but I'm muggle-born," Rose said. "And outside of the wizarding world, the name Potter is beyond common. I think there were four other Potters in my primary school class, and not one of us related to another."

"That's a very good point," the boy conceded with a mock-serious expression.

"See, he gets it. I'm going to be his twin instead."

"You don't get to pick," Hermione stated exasperatedly. "And anyway, he's older than you."

"Plus," said an identical redhead, dropping into the seat on Rose's other side, "the position has already been filled. No further applications are being accepted at this time. I'm Gred. He's Feorge."

"They're Fred and George," Ron said irritably as he dragged his plate back in front of him and started piling on seconds.

Rose looked back and forth between the two boys, obviously ecstatic (for whatever reason) to be sandwiched between the identical redheads. "But I can be, like a substitute twin, right? Like if one of you is sick or something?"

Both twins' eyebrows shot into their hairline. Their eyes met over her head and they then proceeded to have a conversation consisting of head tilting and eyebrow waggling which then devolved into more and more elaborate hand gestures until they decided that they'd carried on long enough and turned back to her.

"We'll see," they said simultaneously.

"But first," the one on her left (George, maybe?) said, "we have to confirm that you are not in fact already a twin."

"Wouldn't do to break up a set," added the other (Fred?).

Rose pouted. "I thought we'd already established that."

"I certainly thought so," Harry added from across the table.

"Oh ye of little faith," said George. "A few quick questions and we will get to the bottom of this."

Rose sighed and planted her elbows on the table, propping up her chin with her hands. "Fine. Ask your questions."

The boys grinned. "It is common knowledge," Fred began, "that Harry Potter's parents are named James and Lilly Potter. What…" he paused dramatically "are your parent's names?"

"Jason and Dahlia," Rose answered promptly. "Clearly not James and Lily."

"Ah," said George mischievously. "Clearly."

"Clearly," agreed Fred. "And yet…"

"Yet what?" Rose asked suspiciously.

"And yet, Jason is almost like James, isn't it?" asked George.

"And dahlias and lilies are both flowers," Hermione added helpfully.

"You're not helping," Rose pointed out.

"My aunt, my mum's sister, is named Petunia," Harry said slowly.

"You're not helping either," Rose said.

"And you're Rose!" the twins exclaimed.

"This proves nothing," she stated.

"It is pretty circumstantial," Hermione said.

"Thank you. See, that was helpful."

"Alright, alright," said George. "Next question then. Is that… your natural hair colour?"

Rose stared at them for a moment, utterly befuddled. "Yes?"

"Ah ha!" Fred exclaimed, and Rose was not the only one who jumped.

"Ah ha what?" she asked.

"While it is common knowledge that Harry here basically looks like his father in miniature," George said, "he has his mother's eyes."

Rose and Harry looked at each other across the table. "So?" she asked.

"James Potter – raven haired, brown eyed. Lily Potter – grass green eyes and gloriously ginger," Fred said, checking off an invisible list in the air. "Harry Potter – raven haired and grass green eyes. Rose Potter – brown eyed and gloriously ginger."

"That's… that's ridiculous," Rose said. "Genetics doesn't work like that, just dividing up the parents' traits among the kids."

"What's genetics?" Fred whispered to George, who shrugged and whispered back, "Probably something muggle."

"Furthermore, lots of people are ginger. You're ginger and we're not related."

"Ah, actually," George said, scratching his cheek sheepishly. "I think we are related to the Potters a couple generations back."

"Really?" Harry asked, suddenly more interested.

"Through the Black line, I think," Fred said. "Mum doesn't really like us to bring up that part of the family though, so I could be wrong."

"Most pureblood wizarding families are related," Hermione added. "I read about it in –"

"Okay, not the point," Rose interrupted. "Red hair is not proof of kinship."

"Cousin, you wound us!" George cried, clutching his chest dramatically.

"In the heart," Fred added helpfully when Rose only leveled George with an unimpressed stare. She turned the stare on him, and Fred waved his hand dismissively. "Fine, fine. Last question then."

"Finally."

"What… is your birthday?"

"See, you should have asked that question first," Rose said. "Because if we don't share a birthday then we obviously aren't twins. Right Harry?"

"Um, sure," he said, a little surprised to be dragged back into the chaos of the charade happening across the table from him.

"Right," Rose said. "I mean, what are the odds of two random people having the exact same birthday?" Hermione opened her mouth to answer, so Rose quickly added, "Doesn't actually matter. The point is, it's small. Miniscule. It's statistically improbable. So when's your birthday, Harry?"

"July 31st," he said.

Hermione, Fred and George turned expectantly to Rose. Even Ron leaned around his brother to see what was going on.

"You're kidding…" Rose said weakly.

"No?"

She stared at him incredulously.

"Your birthday's July 31st too?" Harry asked. The odds were small, and he couldn't help being surprised at the possibility that they shared a birthday after all.

But Rose shook her head once, a sharp denial. "August 1st."

There was silence again as the other Gryffindors took that in. Then Fred began to laugh, followed quickly by George, and both twins slapped the younger girl on the back as they congratulated her on her newfound twin. Whispers ran up and down the table, and further away they could see notes being passed to the Ravenclaw table next to them. There was no doubt that the news would spread from there to the Hufflepuffs. And of course the Hufflepuffs were nice enough that they wouldn't keep something that juicy from the Slytherins.

It was going to be all over the school before the end of the welcome feast.

Rose's face scrunched up, and Harry couldn't quite tell if she was upset or amused or something else entirely. "No one's ever going to believe we aren't twins, are they?" she asked at last.

"Sorry?" Harry said. But he thought it might not be so bad, having someone else with him, dealing with the madness of his sudden and inexplicable fame in the wizarding world.

"Not your fault, I guess," she said, offering him a shy smile. "But just so you know, I get to be the crazy twin."

Yeah, this might not be too bad at all.