A/N: Thanks for the reviews! (*_*) You're so encouraging.

So Karin grabbed the exposition hat and put on a fashion show, hahaha.

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NEUN

TIMELINE X + N

The twins led Homura back to the park. They bought some drinks from a nearby vending machine and claimed a picnic table on a small hill. Homura sat across from the sisters and eyed them warily.

"So," began Karin. "Pluses and Hollows." She stared at her soda can seriously for a moment to gather her thoughts, then took a deep breath and looked up at Homura. "The fact that you have a Soul Gem means I don't have to convince you that souls are real, right?"

Homura nodded seriously. Karin looked a bit disappointed. Maybe she had expected a more dramatic reaction?

Karin took a deep breath. "Okay, so when you're alive, your soul is tied to your body by a literal chain, because evidently metaphors are too abstract for someone upstairs. When you die, your soul gets kicked out of your body and the chain breaks. Barring rare exceptional circumstances, your lifetime pass to that body is revoked and you can't get back in. Make sense so far?"

Homura nodded again.

Yuzu took over. "A lot of people... move on, cross over, or whatever name you give moving to the afterlife—"

"And there is an afterlife," interrupted Karin.

"Yes, there is an afterlife. It's called Soul Society. We'll explain that more later. Anyway, a lot of people move on by themselves. But a lot of people also don't. They have regrets, or don't want to go, or are afraid, or have unfinished business. Sometimes they died so fast that they don't know they're dead. So they wander around, or stay near a certain place that was important to them. These souls are what most people call ghosts. The chain on their chests is what's left of their attachment to their bodies."

Karin took over. "At that point, they're still pretty much themselves. Whole. But when the chain isn't attached to a living body, it starts to disintegrate from the end." Karin's face turned grim. "When it gets to the plate on a soul's chest, the plate dissolves, too. Things get kind of vague here. That plate is connected to this part of a soul that is called the 'heart' or 'mind'. Metaphysically speaking, I mean. I think it's clearer to say their 'humanity'. When that's gone, the soul transforms into a monster called a Hollow. Most new Hollows are mindless bundles of instinct. Their instinct is to eat other souls."

Eyes wide, Homura asked, "Why?"

Yuzu sadly answered, "They're left with animal instinct but they can tell something's missing. They have an actual hole in their bodies that represents their missing 'hearts'. So they hurt and they're empty and all they can think to do is try to fill themselves up with Whole souls— Pluses. But they can never fill that hole no matter how many Pluses they eat."

"I think whoever came up with these terms was some kind of math nerd." Karin mused. "Think of the names like Whole souls are positive integers, therefore Pluses. Think of newer Hollows as empty or zeroes. Then there is a kind of Hollow that loses itself so much it goes into negative integer territory and becomes something called a Menos. Plus-zero-minus."

"What is a Menos, then?" Homura asked with dread.

Yuzu quietly said, "Hollows that get so hungry they start eating other Hollows. They're more powerful than normal Hollows. And the more they eat, the more powerful they get."

"O-kay!" Karin said with a sharp clap. "So. We have ghosts wandering around, and hungry ghosts running around trying to eat the normal ghosts. Things can get pretty wild if they're left to their own devices. That's where shinigami come in."

Homura tipped her head and looked at Karin skeptically. "You are saying shinigami are real?"

"Yep. Basically, shinigami are strong human souls. They come from Soul Society to gallivant around the World of the Living like ghost police. They find Pluses and help them cross over before they can turn into Hollows. They also fight Hollows and purify them. Most of the time, when a Hollow is purified, it goes on to Soul Society, too. Sometimes they were already monstrous enough in life that these creepy skeleton gates will pop up like the world's worst jack-in-the-box and drag their asses to Hell."

Yuzu shivered. "I hate those gates."

Homura stared blankly. "Hell is real, too?"

"For better or worse, yeah."

Homura frowned thoughtfully. "Why do you get Hollows and Pluses here, then? I have never seen them before."

Karin leaned back and took a swig of her soda. "That's because Karakura is something called a jūreichi. Basically, it's an area with a stupid-dense concentration of spiritual beings. There are a lot here to start with, so more get drawn in, on and on. Kyubey said that Witches mostly stick to areas with low... spiritual presence, I think. Witches mostly hunt normal humans. Hollows do hunt normal humans, but they're most drawn to strong souls because they're a more satisfying meal. Hollows are freakishly common in Karakura because of the whole jūreichi thing making even the people who can't see ghosts juuust strong enough to be extra delicious or something. A lot of people here have been exposed to the supernatural so much that they have at least some idea that weird invisible stuff is happening. Some of them may only know they suddenly feel like they should really avoid walking on a certain street or something, but they have at least some sense."

"That's kind of what I was like," Yuzu chirped. "Karin and my brother had always been able to see, but before I met Kyubey I could only hear some and see some blurs. And I got bad feelings about places sometimes. I got attacked by Hollows a few times. It's really scary when you can't see what's attacking you."

Karin sipped her soda and set it down. "So anyway, just that little boost makes the people who live here some kind of delicacy to a Hollow. Kyubey said that most Witches prefer the boring, normal places because it would be more difficult to mentally snare people who have more latent spiritual power. Like... Witches' magic can kind of sneak up on most people and get a Witch's Kiss on them because they have no defenses. But someone with even a small boost in spiritual power takes more effort to snag. And you know how most Witches work— quiet, hidden, pretty much trick people into serving themselves for dinner. Think of them... umm..." Karin scratched her head and stared skyward in thought. "Like... hunters versus trappers. Oh! If Hollows are wolves, Witches are spiders. Generally speaking. There is some crossover... wolf spiders, hahaha I kill myself." Karin grinned. "Anyway, Kyubey says that difference is why even potential magical girls are more likely to notice they've been lured into a labyrinth without getting Kissed and brainwashed." Karin tilted her head. "Have you noticed a pattern like that? Kyubey told me about it, but I only have our experience to go on."

Homura frowned and stared at the table in thought. She clearly remembered the moment in the initial timeline when she had suddenly come to her senses in her first labyrinth, some instinct startling her out of the mental grip of the Witch that had whispered soothing death to her. Had that been an innate defense before a Witch's Kiss completely bound her? And in the current timeline, she had seen a similar result when Madoka and Sayaka wandered into the labyrinth at the mall. And again, when Sayaka and Madoka weren't ensnared by the Sweets Witch. And again, when Madoka followed the flock of Witch-Kissed victims to the television station labyrinth and kept her wits about her enough to counter whatever orders the Witch had given her thralls. There had been examples in other timelines, but those were the most recent. On some level, Homura had always noticed the pattern; she had just never questioned the why of it. Little puzzle pieces shifted into place. Joy of joys, they made an answer that sparked another question.

"Yes," Homura slowly answered after she rolled it over in her head a bit. She looked up at Karin seriously. "Are you implying there is a correlation between magical girl potential and... spiritual awareness, I think you said?"

"Mm-hmm," hummed Yuzu. "Before you became a magical girl... well, I know you said you never saw anything, but did you ever feel anything? Did you ever walk down a perfectly normal street full of perfectly normal people and suddenly stop because you were certain something was... maybe hiding around a corner or something? Or even just felt like... like you couldn't trust your eyes when you looked at an empty space where no one was standing, and felt like someone should be there? Or someone was watching you? Things like that."

"Especially near things like those little roadside memorials for people who got hit by a car or something. Those are dead giveaways. Ouch! Yuzu! Pun not intended!" The sisters tussled for a moment.

Homura tried to think back to the time before she went to Mitakihara. It seemed so long ago now. She hadn't gotten out much before her last surgery, anyway. But the more she thought about it...

"What about hospitals?"

The sisters blinked at her. "Oh, yeah," said Karin. "Especially the bigger ones. Confused dead people can wander around in them if they don't cross over right away. My friend told me that a shinigami assigned to an area with a hospital in it is supposed to patrol the hospital at least once a week to clear them out."

"Karin!" scolded Yuzu. "You make it sound like— like— sweeping up cobwebs or something."

"Isn't it?" Karin deadpanned.

Yuzu heaved a long-suffering sigh. "You're incorrigible."

Homura tilted her head curiously. "What friend told you about... assignments and patrols? Do you know the shinigami?"

Karin flushed and glanced at her sister, who was suddenly grinning delightedly. "Yuzu, don't you star—"

"Karin is friends with a highly-ranked shinigami."

"We're not here to talk about Tōshirō."

"Just all the things he's taught you, right?" Yuzu's smile was a bit too sweet to be called a smirk, but it was sly all the same. She looked at Homura and raised her hand to her mouth conspiratorially. "Most of the fancy explanations Karin just gave come from her asking her friend the same questions."

"Stop saying friend like it's some kind of code word, Yuzu, it's creepy. And I only asked him because Ichi-nii may be smart but he sucks at explaining spirit stuff. And that was after I practically beat it out of him with all his 'wah wah you're safer if you don't know'." Karin glared off to the side with a pout. "Such a waste of effort. Though I guess I can't blame him if those drawings are how Rukia explained things to him."

Yuzu looked mildly confused. "Rukia's drawings are cute. They made sense to me."

Karin grimaced. "Sure. Yeah. Whatever."

Alarmed, Homura asked, "Your brother knows about magical girls?"

Yuzu choked on her soda and Karin's jaw dropped. The sisters snapped their attention back to their guest.

"What? No! No way!" denied Karin. "God, Ichi-nii would kill us, send us to Soul Society, hunt us down there, and give us the third degree all over again if he knew we contracted. Especially why we contracted."

"No, he wouldn't," Yuzu said with a calm roll of her eyes as she wiped her mouth. "He'd just put on his disappointed puppy face and make us wish he had."

Karin considered this carefully. "Yeah, you're right. He's a total sucker for us."

Homura eyed them both oddly. "If he does not know about magical girls, then what does he know and how does he know it?"

"Welllllll," Karin hedged. "That's a long story. The super short version is: Surprise! Our big brother is a shinigami."

Homura looked more confused. "I thought you said shinigami were... souls that came here from the afterlife?"

"Yep!" Karin took a swig of her soda.

"But... your brother is alive. Right?"

"Uh-huh," chirped Yuzu.

"Then how...?"

"There's a long complicated story of family drama and diabolical experiments and all manner of spiritual shenanigans and dead-people politics and god-wannabe megalomaniacs," Karin said while gesturing expansively with her soda, "but you can summarize it as 'Ichi-nii is a freak of nature who will get stronger and do something new every time you think you have him figured out.' He was always really, really strongly spiritually aware, but a few years ago his power just went off the charts and, hilarious as it sounds, he's stronger than a lot of dead people." Karin grinned at Homura's bewildered stare. "This is our family's standard of normal. Evidently my brother even confuses and frustrates the dead guys. Tōshirō has a special twitchy facial expression just for when my brother pulls something weird. It's great."

Homura tilted her head. "If your brother is so strong, why can he not sense that you are magical girls? Surely he must be able to tell you have power?"

"According to Kyubey, when he makes us magical girls all that happens is he focuses and concentrates the powers our souls already had. So spiritually aware people who knew us before we contracted felt our power get stronger and more controlled. It would be weird except the timing of the change is perfect."

"What do you mean?"

Yuzu took over with a smile. "When we contracted, we were only two years younger than our brother was when his powers suddenly got stronger and he started seeing Hollows on top of Pluses. Then he got strong enough to fight. Kyubey says that like with a lot of things, girls mature spiritually sooner than boys. So us getting stronger was kind of expected."

"Especially with our parentage," Karin said with a smirk.

Homura frowned, but took the bait. "What about your parentage?"

"Oh, nothing much," breezed Karin. "Just that our mom was spiritually strong enough to fight Hollows as an uncontracted human and the old man is a shinigami. Former captain, if you can believe it. I know I can't."

Homura froze in shock. A moment later, she sputtered, "What? B-but— How? If he's a— a spirit, how is he a doctor here? How does he have human children? And his power— I didn't sense..." She trailed off. Actually, she hadn't bothered really paying attention to power in anyone but the twins. The whole town was like a faint buzz of magic in her senses, now that she thought about it. Isshin hadn't particularly stood out, though.

"My friend explained that," answered Karin. "The shinigami invented these fake bodies— gigai. If they need to blend in with the living for some reason, they possess the fake bodies. Then they ditch the body if they have to fight. When Tōshirō visits me, sometimes he borrows a fake body so I won't look nuts talking to thin air and he can help me destroy other teams in soccer. He doesn't feel super strong then, either. He told me that strong shinigami have to seal a lot of their power when they come to the World of the Living and that there are special fake bodies that can seal even more. His guess is that Goat-Face has something like that."

"Wait, your friend guesses? Didn't your father tell you about this?"

Karin snorted. Yuzu laughed. "We're waiting for Daddy to tell us. We got the basics of the situation when we got our brother to tell us about all the spirit stuff. He didn't think some of the technical stuff was important when Daddy told him and he wasn't very good at explaining some of what he did know."

"So I asked Tōshirō, my walking shinigami encyclopedia." Karin smiled smugly. "The old man doesn't know we know about him. We convinced Ichi-nii not to tell him. We're gonna see how long it takes him to decide to tell us and then be totally unsurprised or mess with him some other way. Ichi-nii agrees it should be hysterical."

Homura stared at them strangely and pondered the Kurosaki family's sheer bizarreness.

"I think we got off track," said Yuzu. "Shinigami purify Hollows by fighting them and breaking their masks with their special weapons called zanpakutō. Every shinigami— every soul— has a different weapon. They all start out as swords, but stronger souls sometimes change them into other weapons that match their personalities— you know, like magical girls have. When a zanpakutō breaks a Hollow's mask... um..."

"Math again, kinda," Karin supplied. "The shinigami is pretty much a super strong Plus. So they stab the Hollow with all their... plus-ness... and it cancels out the... minus-ness and purifies the other soul. I hope that makes sense. Shinigami also use their zanpakutō to send normal Pluses to Soul Society by stamping them with the pommel like I did earlier. When the weapon purifies a Hollow, it then also sends the purified spirit to Soul Society. It's a neat little setup."

"So you see," Yuzu finished cheerily, "Shinigami are to Hollows as magical girls are to Witches. Kinda."

Homura's mind whirled, connecting dots, asking questions, and generally feeling overwhelmed. I wonder if they've followed that thought to its logical end. Or could the Incubator have told them about the origin of Witches? Do they know about it all but aren't saying anything because they think I don't know? She set that line of questioning aside for another time.

"You say these— zanpakutō?" Homura said slowly. "You say our weapons are like them. If that is true, why do we have to give Grief Seeds to Kyubey? Should our weapons not purify them, if the analogy holds true?"

"Kyubey said our weapons are imperfect replicas of zanpakutō," said Yuzu.

"Tōshirō told me that shinigami get their zanpakutō by being given a blank sword that absorbs the shinigami's power over time," said Karin. "So they're given something to focus their power as quickly or slowly as they need. Kyubey said that what he does when he makes our Soul Gems is force our souls to crystallize and focus our power by themselves— and very quickly. So the weapons we get are approximations of what we'll get if we become shinigami when we go to Soul Society. They're just not complete in this form. Not enough to truly purify Witches."

"Our weapons can purify Hollows, though," added Yuzu. "But Witches aren't Hollows."

Homura braced a finger along her jaw line and leaned on one elbow, a vague idea bubbling in her mind. Aside from something about that striking her as plain wrong... "If magical girl weapons work on Hollows, do shinigami weapons work on Witches?"

Both sisters shrugged.

"We don't know, and Kyubey says he doesn't know, either," said Karin. "He said that even though Witches are similar to Hollows, they work differently enough that he's never heard of a shinigami deliberately seeking out a labyrinth the way they deliberately hunt Hollows. I'm good at math, but when he starts talking inversion this and quantum that, he loses me. It boils down to Witches being so good at hiding themselves Kyubey has never heard of a shinigami finding one. Or at least not surviving finding one. He told us that, hypothetically speaking, a strong Witch could probably trap a weak shinigami."

Yuzu put her elbows on the table and propped up her chin. "Kyubey says that's why magical girls are so important— shinigami can't sense labyrinths, but magical girls can. Magical girls protect people from the Witches. He said that a long time ago, the shinigami noticed magical girls purifying Hollows and helping Pluses cross over, and that it... didn't go very well."

"He said shinigami get twitchy about living humans having shinigami-like powers," Karin clarified, "and they were especially stabbity about it in the past— Ichi-nii's stories back that up— so it's a neat little bonus for Kyubey that Witches tend to avoid the more spiritually-dense areas where the most shinigami are. It helps him protect magical girls. Historically, he had to worry about protecting magical girls from the Witches, the Hollows, and the shinigami."

"Kyubey actually took a risk contracting us," said Yuzu. "Usually, he avoids the jūreichi wherever it happens to be at a particular point in history."

"That's why Kyubey doesn't actually come to Karakura. We have to go out of town a ways to give him our Grief Seeds."

"We've tried to tell him that the shinigami seem to be more tolerant now, but he refuses to approach the shinigami. He saw what happened when the Quincy— a group of humans who were spiritually gifted enough to fight Hollows— wouldn't obey the shinigami."

Homura raised a brow. "And that would be?"

"Genocide," Karin declared bluntly. "Over two hundred years ago. Ichi-nii and Tōshirō both say the hardliners in the shinigami government that pushed that agenda all got assassinated in the last war, though, and the new government hasn't gone after those survivors they know about. Since the war, anyway."

Regret weighed on Yuzu's face. "We wish Kyubey would work with the shinigami, but we can't blame him for wanting to protect the magical girls. He said he had contracted a few Quincy girls and he saw them get killed. I guess that stays with you."

Homura furrowed her brow, trying to reconcile what she knew of the Incubator's methods with what the twins were telling her. Aside from the girls ascribing such foreign concepts as concern to the Incubator, she could kind of see how the two angles could mesh, but would have to think on it. However...

"If Kyubey avoids Karakura, how did he contract you?"

Karin rolled her empty soda can in circles along its rim. "That's an interesting story, actually. That Tokyo field trip we're using as cover with Goat-Face really did happen."

Yuzu smiled sadly. "We met Kyubey at the botanical gardens."

Homura leaned forward and held her chin in her hands. She stared intently at Karin. "Tell me."

Karin rolled her shoulders, took a deep breath, and began to tell the story.

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A/N: Picture, if you will, Ichigo trying to explain shinigami stuff, panicking, and digging out Rukia's drawings to use as a visual aid. Picture that trainwreck.

Further geekery I couldn't believably fit into a teenager's explanation of Pluses-Hollows-Menos, no matter how smart I have her: In my mind, the power levels of the categories are expressed as a parabola with a positive slope at vertex (0,0). X-axis would be "degree of wholeness/hollowness" and Y-axis would be "power level," such that the farther one goes left/Hollow, the more powerful one gets, and the farther right/Whole/Plus/shinigami-like, the more powerful one becomes. Movement to the right would be through positive means such as training and natural growth; movement left would be due to further corruption, such as Hollows eating Hollows. It's been several years since my last math class so let me know if any of that sounds off.

This chapter was replaced with an edited version on November 1, 2019. Reviews with timestamps before that date refer to a slightly different version of the chapter.