Ichigo was in the mountains, far from Seireitei, his reiatsu hidden by a Kido barrier he'd made himself. He was dressed all in black, but not a shinigami's shihakusho. His blade was long and black, an odachi with a 'ban' or manji symbol for a guard, a long black chain coming off the end of the handle.
It'd taken four years, but he finally had bankai again, and he'd done it properly, without using Urahara's risky cheat. It was the bankai he'd gotten when Zangetsu and his inner-Hollow had merged.
Rukia, who was sitting on a boulder with Sode no Shirayuki over her knees, said, "Is it different from what you expected?"
"Nah. This is pretty much it." He didn't think it was different at all from what he'd had once Zangetsu and his inner Hollow had merged. "Super speed, flight, and a better Getsuga."
Rukia said, "There's no way your outfit changes so much just so you can look flashier. Zangetsu can't be that vain. There must be some use to it. And that long chain as well."
"I guess. I need to experiment." It was still strange to think that he had years, even decades, to master it.
Rukia nodded, took a deep breath, and a child made of snow appeared. Perfectly white and feminine featured, with black pebbles for eyes.
"Why so surprised?" Rukia said.
"I'm not," he said. "I knew you had to be close." He thought she might've gotten bankai already if combining with her younger self hadn't changed Sode no Shirayuki in subtle ways. He stared closely at the zanpakutou spirit, carving it into his memory. It was a very private thing that Rukia was letting him see.
Rukia said, "Sleeves of Snow. I used to wonder why it was called that and yet my shikai only ever made ice. But I understand now. She isn't an ice and water type at all. She's a freezing type. And when I give the command to shatter, my enemies turn to snow." She raised her blade, and from its own self, the zanpakutou raised its own.
Rukia said, "Some space, if you please."
Ichigo leapt away, shouting, "I'll keep watch." They still had four days of leave, and defeating your materialized zanpakutou, was hard, not time consuming. It was everything leading up to it that took years and years.
It was much too cold inside the barrier. Even at the edge of it, as far away from Rukia and her zanpakutou as possible, Ichigo would quickly begin to shiver.
So he stayed outside of it, a good ten yards past the barrier, cold radiating off its walls, and kept his hands shoved up his sleeves, enjoying the warm light of the sun.
At mid-afternoon on the third day, the barrier broke.
The cool air turned frigid in an instant. Frost sheathed his eyelashes, and he flared his reiatsu just to avoid injury.
The landscape, extending beyond the barrier, straggling on even a little ways past him, was white, covered in ice. What water was in the air had frozen and was falling. Beneath the surface, he was sure, the earth had been frozen into permafrost. Rukia was at the center of the circle of ice, dressed all in white, and her hair was pure white also, as if turned to snow.
Ichigo moved in cautiously ready to shunpo away at any moment. He didn't want to have to defend himself if she wasn't in control of her bankai.
Rukia raised her zanpakutou slowly, examining it.
"Well?" said Ichigo.
"This," Rukia replied, "is very dangerous."
"It's bankai," Ichigo replied. It was supposed to be dangerous. He was glowing with even more reiatsu to stop himself from shivering. As if he were in a fight with Kenpachi.
She spoke slowly, carefully. "I believe I am currently at absolute zero, and I feel as if I could somehow become colder still. As if I could reach some temperature on the other side of infinity."
Slowly, she began to thaw.
When Ichigo reported for duty, Byakuya stared at him. He began to fidget, wondering if he'd somehow lost track of the dates and come back a day late.
Byakuya said, "3rd Seat Kurokento Ichigo."
"I'm 6th seat," said Ichigo.
"Not anymore. Go challenge the 3rd seat. Win. Don't dramatize it."
"I would rather not."
Byakuya said, "You hide your true strength, but not well enough to hide that you've grown. Take the promotion."
Ichigo gave a half nod, showing just enough respect to avoid comment, and went off to find the current 3rd seat. Having obtained bankai, he could probably take Byakuya in a fight. It'd probably been too much to hope to pass himself off as anything less than a 3rd Seat. Hopefully Rukia would do better. She had less reiryoku and was more accomplished at hiding it.
He spotted the bald man who'd always reminded him a little of Ikkaku. "Iemura," he shouted. "The Captain wants us to do a seating competition." He drew Zangetsu but didn't release his shikai. He wouldn't dramatize it, just like Byakuya had said.
As she carried out her duties, doing paperwork, training, and going on a day patrol, Rukia kept expecting someone to notice. Kaien. Miyako. Ukitake. But she only received polite questions about how her leave had been, and exhortations to learn to relax when she said she'd spent most of it training.
She had come into the Division as the tenth Seat, and a little over 4 years later, she was still the 10th Seat. It wasn't as if she hadn't shown improvement. As good as she'd become at suppressing her reiatsu and hiding her true reiryoku (and she'd become very, very good indeed) she'd attained bankai, of all things. She did seem stronger. And she in no way hid her growth in skills. She'd improved her swordsmanship and her hand-to-hand, which had been good from the start. She'd brought her shunpo to a point of high expertise: Nii-sama had begun to show her secret techniques, and while she hadn't mastered them, her shunpo had been above average for a seated officer even before she'd come to the past. As for Kido, she'd verged on exceptional even before coming to the past, and while she didn't show her skills off, she'd ceased to hide them, and worked openly at improving them. The title of Kido Master wasn't out of reach, a fact that her superior had surely noticed, considering how much they asked her to help others improve at it.
From a skills perspective, she couldn't be trailing anyone but Captain Ukitake and Kaien, and perhaps, just maybe, Miyako. She did all her paperwork on time, and with friendly little drawings where appropriate. She didn't make any mistakes on her missions. Instead, she was praised for her good sense, and for 'not acting like a rookie.'
Yet no promotion had come. She wondered if she should request a Seating battle, but Division 13 seldom handled matters in that way. It was considered poor form to not simply wait for higher officers to approach you about it.
Ichigo hadn't had any problems getting promotions. Promoted to 3rd Seat his first day back from leave. Obviously, he wasn't as good at hiding his strength, but still.
On her fourth day back, Kaien called her into his office.
She suppressed her nerves, and listened calmly as he told her that she'd be going on a two week assignment to a place called Nuu Yoruku, which had an unusual quantity of reishi for a city outside Japan.
She made her goodbyes to Ichigo, Hisana and Nii-sama, confirmed with Nii-sama that he hadn't put in a request for her promotion to be delayed, and went to Nuu Yoruku wondering if the problem lay with her.
A month after returning, having spent much of that month torturing Ichigo with questionably on-key renditions of popular Broadway numbers, she got promoted to 9th Seat.
Budgets were upon them, and the amount of paperwork had expanded. Ichigo had been grounded just to help with it. He, Byakuya, Suzuki, and the secretary, whose name turned out to be Ringo—she actually was a 17th Seat, and wasn't bad with her zanpakutou—were all spending far too much time in the office, filling out forms and squinting at bad handwriting.
Ichigo did his paperwork in pen. Better than the brush.
Out of complete silence, without introduction, Byakuya said, "Hisana has expressed a desire to visit the Division regularly."
Suzuki, Byakuya and Ringo all exchanged surprised looks at that unexpected announcement. Setting his brush down, Suzuki cleared his throat and said, "Very understandable, Byakuya-sama, but this is not a proper place for a lady, and coming would only make her assimilating into her circle more difficult."
Byakuya hmmed as if he agreed, yet looked doubtful.
Taking Suzuki's lead that it was a personal matter, not a Division one, but pushing it even a step further, Ichigo said, "Byakuya, you know Hisana better than anyone, but there are parts of her you can't ever know. Like what she's like when you're not around. Hisana's a workaholic. She stops working pretty much just for you, and sometimes Rukia. She's probably bored silly."
Byakuya said, "She is well-occupied. She has a stocked painting studio, and she busies herself with her Kido instructor."
"Those are hobbies, not work. It's not like Lady Kuchiki can sell her paintings at the market, and she does nothing with her Kido skills but have them. So embrace her coming down to the Division, and screw the impropriety. She'll do loads of improper things, in a dignified way. She's a great cook, and Rukia's interested her in western baking; she'll make everyone treats. She'll pitch in with paperwork where she can. She's gotten good enough with Kaido to heal simple injuries, right, and skilled enough with Kido to tutor the newbies a bit? The rank'n'file will think she's an angel. Some of them might even start liking you by extension."
Byakuya's expression was cold. "Are you implying I'm not well-liked?"
"You're feared, respected and even worshiped, but there's like six of us total who actually like you, and oh, you're being sarcastic." Byakuya knew he wasn't well-liked. Ichigo didn't think Byakuya cared, but it was hard to be sure.
"I will consider it," Byakuya said, and they all returned to their paperwork.
District 65 was as they remembered. Moderately drab, with half-paved roads and a few artificial ponds that formed nuclei of what were almost parks. The endless fields, some half of them devoted to rice patties, took up most of the water brought there by aqueduct.
Ichigo had expected the apartment complex to look more rundown than when he'd seen it last, but instead it looked to have gotten a new coat of whitewash and a new roof too.
He supposed it'd been time. The building, like most of the area, was Kuchiki owned, and Byakuya wasn't a slumlord. He'd want his poor tenants living in respectable poverty, with clean faces and roofs that didn't leak.
Ichigo and Rukia had been sure to arrive on rest day, and went up the stairs until they reached the apartment.
Ichigo had been afraid they'd moved, but Rukia smiled as they got closer, and he knew she was sensitive enough to sense even people with no particular reiryoku.
She knocked on the screen.
The apartment was a little nicer than when they'd been there last, not long after the wedding. It had wide, thin cushions, a nicer table, and two folding chair in a corner, evidence of the gradual encroachment of Living World furnishings and styles.
Tokihiro served them tea, a nostalgic ritual for Ichigo, and doubly so for Rukia.
The tea was an icebreaker, but then came the usual questions about how life was going, and Ichigo was asked if he was still the 7th Seat.
Uncomfortable, Ichigo rubbed his head. "3rd Seat."
That caused a moment's silence. They didn't know much about the Gotei, but they did know that the lower the number, the stronger the shinigami, and three was a number startlingly close to one.
Rukia said, "How about yourselves? The place looks nicer than before."
"We'll be moving to a bigger apartment soon," said Subaru. "Me and Toki have been apprenticed to scribes, and Nobu is an assistant to a field manager."
"How lucky," said Rukia, looking satisfied.
Ichigo was momentarily surprised at Rukia having apparently thrown her weight around as Byakuya's sister-in-law. It wasn't like her to use her position. But then, it wasn't for her benefit.
Rukia said, "And Renji? Where's he?"
Subaru said, "The Shino Academy examiners came through 5 months ago. Renji left with them. I thought you would've seen him by now."
Rukia looked simultaneously startled and pleased. "That's a few years earlier than it might've been. But it's no wonder he hasn't come to see us. Academy students don't have much freedom to leave the Academy Grounds, especially in their first year, and they're strictly advised against visiting Divisions."
That led to several hesitant questions about what Renji was likely doing with his days at the Academy, and further, what his eventual duties as a shinigami would be like, and Rukia turned a mission about an unusually insane Hollow fixated on red-headed women in District 28 into a ridiculous, rollicking tale, complete with illustrations.
Tokihiro invited Ichigo out for a walk, and Ichigo could hardly refuse. Tokihiro strolled, pointing out trees and giving their names, gesturing to a little culvert he had dug to channel water out of a depression in the road and into a pond.
He hadn't done it on orders, but because he'd thought it would improve matters. Wherever Tokihiro was, he treated it as his garden. Ichigo had been used to that once, but time and distance had made it precious and startling again.
Stopping before a persimmon tree, Tokihiro said, "It's lucky, us all getting apprenticeships like this."
"They must recognize talent," Ichigo replied.
Tokihiro said, "You're the 3rd Seat of Division 6."
"I hear that Kuchiki-sama himself is the Captain of Division 6."
"And I hear he married a woman of Rukongai. Kuchiki Hisana-sama. Formerly Kotsuki Hisana. Kotsuki is the name Rukia is using now."
Ichigo was silent.
"They look real similar, but we were lucky to discover the relationship."
Tokihiro sighed, hand on the tree's trunk. Ichigo wondered what he had to do with it. Watered it, pruned it, dug a bowl around it? Some small action to improve the world.
Tokihiro said, "We'll never be in position to repay. But if there's ever, by some chance, anything I can do, I'll do it."
There was pride in Tokihiro's stance, so Ichigo said, "Someday, I may call that in."
They stayed for two pleasant if occasionally awkward days. As they left, Ichigo wondered if they'd ever visit again.
When they returned to Seireitei, Rukia wanted them to go visit Renji at the Academy.
Nah," said Ichigo. "I'll see 'im later. You do it."
Rukia looked at him oddly.
"Don't be thick. You're the one he grew up with." How the hell was Renji supposed to show off for her with him there, being an imposing 3rd Seat and all that?
So Rukia ran off to the Academy and Ichigo crept into Division 6, interrogated Saito to make sure he wasn't desperately needed for anything, and snuck into his room. He had three more days of leave and he intended to enjoy them by lying on his back with a pot of good tea and reading through his backlog of bootleg Human World manga. Tezuka Osamu was publishing his early works, and it was a pleasure to watch the legendary mangaka develop in real time.
Hours later, Rukia bomped in through the window, landed on his stomach hard enough to make him go oomph, and chattered as cheerily as she ever had.
"Renji's doing very well. Advanced Class 1, of course, and he's really been practicing his Kido. Not that he'll ever be much at it, but it's helped in other ways."
"Bitch," he gasped, getting his breath back. "You stomped." Right on his belly.
Rukia said, "It's hardly my fault you let down your guard. You're out of practice, Ichigo."
Out of practice at being suddenly attacked when he was peacefully reclined. A consequence of not living with his father. He got to his feet, read to show her who was better at Hakuda.
Reading his intention, Rukia said, "Really, Ichigo? Is a tap like that more important than hearing about Renji?"
Ichigo glowered, and subsided. "Fine." He'd get her later, when she least expected it. Not a reciprocal stomp, because as strong as she was, she was still so small, but something. "How's Renji?"
"Very well, as you would've heard if you'd been listening. Advanced Class 1. He's made rivals with Hisagi Shuhei."
"Okay." He had no idea who that was.
Her eyes narrowed. "A man with black hair."
"Uh-huh." She'd just described 60% of shinigami.
"He has the number 69 tattooed on his cheek."
Ichigo was taken aback. He should remember someone like that. Had they really met? Rukia seemed to think so. Probably a hello and goodbye after he'd saved Rukia but before he'd left Soul Society. Ichigo said, "Why does he have a tattoo? And why 69?"
"I don't know. But he's talented. Many people have already marked him as a future Lieutenant. I think he might do well in Division 9."
"Good for him," Ichigo said. He searched his memory. "I've got nothing." He shrugged. "When's Renji's next day leave? We'll show him around."
"No," said Rukia. "What are you thinking? We may visit the Academy once or twice, and happen to speak to him while we're there, but an Academy student can't pall around with two Seated Shinigami. We'll wait until he graduates. It's only five years."
It still surprised Ichigo how Rukia would speak of five or 10 years as if it wasn't long at all, but as Ichigo got older, he slowly found that perspective less and less unnatural.
Canonically, in terms of the manga, I don't believe we actually see Rukia's zanpakutou spirit. I think we only see Ichigo's, Renji's and Hitsugaya's. Hitsugaya's is a dragon. Renji's is a baboon with a snake for a tail. I haven't actually watched the Zanpakutou rebellion arc, but I've seen a little about it. I understand that lots of people like it, and maybe I would too if I watched it. (I stopped watching the anime sometime during the battle for Karakura and just read the manga from there.)
But choosing to make the zanpakutou into people is a bit disappointing in my mind. I generally don't find people very evocative. The non-humanness expressed by Renji's Zabimaru and even somewhat by Ichigo's spirits is to me much more interesting. Let the characters be people, I say; let their Inner Spirits be something else. And so I will probably never write a Bleach fanfiction in which Rukia's zanpakutou is a white-haired woman.
There is such a thing as temperatures below absolute zero. When I read the description, I do not understand. It sounds to me like an accounting trick. But it is apparently a meaningful one.