Author Notes: I'm really grateful for the feedback I've been getting so far! Thanks for all the comments and follows, everyone! Remember, if I've made a terrible mistake, please tell me so I can fix it!

3: The Difference a Number Can Make

Breakfast, first. The difference there was jarring enough to Yumichika that it set him off for a few days. Rather than the free-for-all in the Eleventh, the mess hall was closer to the school cafeteria at Ichigo's school. He joined the line, followed the lead of the others, picked up a tray, and joined the line. The cadet on mess duty gave him precise scoops of rice, natto, a rolled omelet, and a cup of miso soup. It all looked a bit gray, and Yumichika didn't see anything that looked like it had been cut off of an animal. He also hated natto, and was about to ask for an extra omelet to make up for it, but got shoved along in the line. He glanced to the young recruit next to him. "Is it always like this?"

She looked completely taken aback. "You're talking to me?" She whipped her head around quickly, then nodded. "It is, yes. Captain Kurotsuchi has personally designed every meal in the rotation to be precisely balanced for optimum health, brain function, and nutrition. Some items have added nutrients and vitamins, depending on the kind of work he expects to get done on certain days." Her eyes narrowed with suspicion as they edged further down the line. "Why?"

"Just, in the Eleventh, you just take what you want, and-" The girl laughed, cutting him off, and filled her cup with hot tea from a dispenser.

"That's right, you're our borrowed guinea pig!" She patted his back. "The Captain warned us about you. No wonder." She quickly abandoned him where the line let off.

Yumichika would have blushed and protested at being called a guinea pig, except he had used the words himself to get into this situation. It's not as though there were anyone to listen, because he sat and ate all by himself. Every other meal was the same, but for the kind of food offered, and even that all started to taste the same.

He had a regimented schedule, lines drawn as neatly as those on their trays at lunch. A scant fifteen minutes in the shower?! He barely had time to get a basic bit of makeup on! There weren't even bells or whistles to mark when it was time to move from one task to the next, they all just seemed to know. Yumichika was nearly led by his nose as he tried to acclimate.

Kurotsuchi gave him instructions to teach hakuda to a few selected squads every day, and the rest went off to their other duties deeper in the bowels of the SRDI building. The yard was sparse, just a broad expanse of packed dirt surrounded by white and gray windowless buildings, and despite their "ideal" diet, most of the members he'd been given to train were lethargic, or perhaps just less than enthusiastic about their lessons. He knew he shouldn't have been surprised, since they were nerds, not warriors. He enjoyed tossing them around as much as he could, but with none of them putting up much resistance, it wasn't as fun. Sure, he was stronger than about 95% of the Eleventh Squad, but at least they put up a fight! At the end of the day, though, they seemed to be learning, and they could all recreate whatever he'd demonstrated with at least visual accuracy. The power just wasn't there, so Yumichika couldn't pour his heart into it.

He was given an empty room with a single bunk and a storage crate for his personal belongings, spartan but functional. It wasn't their Third Seat's usual quarters, but Yumichika hadn't expected much. He had a place to put his makeup and a few personal effects, his yukata and casual clothes for nights in and days off. He didn't have a chance to use them. Once the day's work was over, he would settle in and lay alone. He didn't get missions outside of Soul Society- no Hollow-hunting for him- or even sent on patrol around the Rukongai. Yumichika appreciated that he wasn't being put directly into serious danger, but he had the slightest sneaking suspicion that Kurotsuchi didn't want him to have a chance to run away. It didn't matter: it just boiled down to him having nothing to do at night. Nobody to see or talk to, anyway. He probably could have gone out to see his friends, but could have and would were different things. After breaking away from Ikkaku, seeing him again would just be like swallowing his sword. He instead sat alone, flipping through back copies of the Communication borrowed from the division's library or any other interesting-looking book he could get his hands on. He had expected to be lonesome, anyway, but for his zanpakuto and the unknown. The former clucked and tutted him whenever he tried to meditate with it, so he was left with the latter. Once a night, just before drifting off to sleep, he would meditate and sense through his reiatsu.

He first discovered that change after two weeks. It was a small disturbance at first, like a knot in the ebb of his energy flow. He didn't let himself get excited- it could just be a minor whorl from the change in scenery, or maybe it was whatever Kurotsuchi was putting in the food. It didn't stop him from talking to it anyway:

"If you're there, I'd better be careful, right?"

It only seemed to grow day by day, the knot winding tighter and spreading, until after five weeks of waiting, he felt the knot in his soul try to entangle him. It was like a pair of tiny, tiny hands clasping around his fingers, and he cried out when he felt it.

"You're... you're there! You are!" He crushed his reiatsu around it, as if he could embrace it (or him, or her, or anything) and enveloped its energy in his. It was a tiny, new soul, but it was already a fine shade of deep, dark purplish-blue. He couldn't tell its shape just yet, or perhaps it hadn't decided, nor could he tell anything else about it, but it was there and that was all that was important. Caught up in the wonder of it all, only one word came to his mind: "Ikkaku..."

That was the first night Yumichika cried himself to sleep in the Twelfth Division. He was certain it would not be the last.

Once he got over the first crying bout- somewhere around dawn- he knew his first step would be to tell Captain Kurotsuchi. Approaching his office door, away from the peachy light of the early sun and into the stark fluorescence of the SRDI's rearmost building, where he'd been told the Captain kept his quarters, he could only wonder what his Captain would say.

Kenpachi would have grunted and raised his eyebrow, no doubt, much like the way he had first looked at him and Ikkaku together. Then, he would have gotten over it, with a "Don't let it get in the way of your fighting," and going back to whatever he'd been doing. Yachiru would have launched herself at him like a rocket and hugged his belly and asked when her new playmate would be here. Ikkaku...

… ah, who knew Captain Kurotsuchi's door would be so close?

Yumichika knocked twice. He wasn't surprised to hear a sharp, "Who dares?!" Of course the Captain didn't sleep. Yumichika was nearly sure he didn't eat, either. It would be a wonder if the man's heart ever beat even once.

"Officer Ayasegawa, Captain Kurotsuchi." The words tasted funny, like vinegar and iron on the back of his teeth. He'd always addressed him- what little he'd addressed him before- as Captain, but never meant it as "my Captain." He still wasn't sure he did. "Captain, about our experiment?" He hoped he caught the underlying meaning.

He did, and the door opened a crack. "Oh?" Kurotsuchi had no makeup on yet. Yumichika didn't think he'd ever seen the man's natural skin before, and from the way he scrabbled at the steel jamb, Kurotsuchi seemed to intend to keep it that way. "Do you have news?"

Yumichika felt a lump in his throat. "I guess you could say, step one complete." He rested a hand over his middle, over where his belt was tied. The door promptly slammed shut, and Yumichika found himself shivering with unspoken emotion in front of a cold steel slab. Kurotsuchi could be heard through it nonetheless, sounding as pleased as he'd ever heard him:

"Excellent! We'll begin the study later today! Carry out your morning duties as usual." Yumichika faintly heard footsteps retreating from the door, and took that to mean "dismissed."

Nemu brought her tray over to Yumichika at lunch time, and put down a very large Styrofoam container beside it. "Please drink this," she instructed with the same mild interest with which she approached everything.

"Why?" Yumichika peeked inside- it looked and smelled like water, but then, Kurotsuchi had played a similar trick on Captain Ukitake.

"In order to perform a fully accurate ultrasound, we will need to lift the bladder away from the mock uterus. It will take approximately thirty-two ounces of water to fill your bladder and fully expose the organ under it." Nemu dabbed at the corner of her lip with her napkin, and Yumichika realized she'd already cleared her tray.

"Uh." He cocked his head, then answered, "I don't remember hearing about this." Nemu apprised him, and he felt immensely stupid. How would he know, anyway? Nemu didn't scold him, to his relief.

"Our machine is considerably more sophisticated than the one at the Fourth Division. I am not certain how theirs works, but this is required for ours. We'll also be performing a three-dimensional scan, so it's vital you are prepared." She moved her tray aside. "I can assure you that it's water. If you'd prefer, you can pour it out and refill it."

"Eh. I submitted to this, anyway." He took the first sip- tasted like water- and gulped it down in small slurps.

Unpleasantly full and sloshing enough to make him nauseous, he let Nemu escort him down into the belly of the Institute. It seemed Kurotsuchi had cleared a room used for a previous experiment out to make space for this one, based on what he hoped was a whole lot of unnecessary, for lack of a prettier word, stuff (detritus, maybe?) plugged into the walls, with tubes and multicolored wires and cords everywhere, and a table still littered with glass tubes and beakers and overflowing drawers. The Captain was still putting a few things together, plugging cords into a monitor and some unfamiliar equipment. Unfamiliar to him, anyway. He could hazard a guess as to what the reclined, paper-covered chair was for, at least, even as Nemu gestured to it. "Please, remove your clothing and make yourself comfortable."

Yumichika disrobed, folded each article into neat, perfect, pretty little squares and set them aside, despite the Captain's apprising eye running over his nude figure, and hopped onto the chair. He realized he had no view of the screen from where he was, especially when Nemu made him lie flat back. He tried to sit up, but was thrown back when Nemu applied something cold and gelatinous to his midsection. "Sh-! That's cold! You could've warned me!"

"Do shut up." Kurotsuchi whirled around, a white sensor wand in his hand and amusement in his face. "And hold still, while you're at it." Yumichika turned his nose up, but put his head back. He pressed the wand against Yumichika's middle, and pulled the cart with the screen on it into closer view. Not Yumichika's view, either. Yumichika tried to sit up to see, but Kurotsuchi tutted him and he lay back down. He moved the wand right and left, and Yumichika noticed him holding a button on the side down in a few spots. He slowly swiped, holding it down, then put the wand aside and took a few notes. Nemu picked the screen up and swiped her fingertips across the surface, and Yumichika could see the images changing from the patterns of light shining on her clothes.

"Hey, can I see my baby?" He said the word "my" with a little more emphasis than he should have, but he sure as hell couldn't let this fly! Kurotsuchi tsked him and took the screen away from Nemu.

"It's an experiment. If the subject know the progress in advance, it risks the results. I wouldn't want you changing your normal behavior because you've seen a data pattern you don't like!" He whisked it back to a docking station Yumichika could see, but the screen was already black. Yumichika wiped his stomach off.

"Well, how about the heartbeat?"

"Ha!" Kurotsuchi laughed sharply. "Idiot, there's no heartbeat."

The blood drained away from Yumichika's face all at once. "Wh-what?"

"Yes." Nemu took a book from the side table and opened it to a marked page. "At five weeks after conception, there is no heartbeat. There is no heart." She showed him a diagram that only looked like a blur of purple and pink blobs. "You have only just entered the embryonic stage. At this stage, the baby is the size of a sesame seed. The heart has started to form chambers, and even then, it will only just be a tube performing vestigial tasks." Yumichika nodded dumbly, because he got the "your baby doesn't have a heart to beat yet" part, and she closed the book and hugged it. "Next week, you should be able to hear the heartbeat."

"We should, Nemu." Kurotsuchi said the word "we" with much more emphasis than necessary, and Yumichika's ears burned.

He could have complained, but this was part of the agreement, wasn't it? Certainly, Kurotsuchi could revoke his contribution as quickly as Yumichika could back out on his. He wouldn't put destroying his baby beyond Kurotsuchi's limited morals.

It only reminded him that if he were back in the Eleventh, he would be going to Unohana, and she'd give him a picture to take with him, and he and Ikkaku could fawn over it for days. Renji had shown him a few pictures he'd had around from Byakuya's first few ultrasounds. There wasn't much to look at, but Renji had said that he was happy enough just to have that. Unohana would let him hear the heartbeat when it could be heard. A few seconds would be enough for him. He could just replay it in his head whenever he wanted if he heard it once.

Kenpachi would be begrudgingly happy for him, in his cantankerous way. Yachiru would be overjoyed. Ikkaku...

God, he missed his squad.

Yachiru caught Ikkaku at it for the nineteeth time in the month since Yumichika had gone away, so this time, she was dead-set on getting a straight answer out of him. She crept through the grass of the lawn between the barracks and mess hall towards him, as quiet as a cat on quaaludes, then jumped onto his head and covered his eyes. "Surprise, Cueball!"

"Gah!" Ikkaku, staring vacantly off into space up and over the Division wall until just a moment ago, flailed until he could get a grip on her. "The hell, Yachiru?!"

"You were in outer space!" Yachiru held her hands out as Ikkaku pried her off. "You gonna try and be a rocketman?"

"Shut up!" He put her down, but she put her hands on her hips with a pout.

"It's 'cos you miss Yun-yun, right?"

"No, that asshole can do whatever he wants." Ikkaku hocked a thick wad of spit at the wall, then glanced up over it again. He could just see the top of the SRDI building just past the trees around the barracks. "It's not like he's that far away."

"But'cha haven't seen him. I heard Pineapple-head askin' why he's not hanging out with ya no more."

"Just busy with his temporary squad, I bet." Ikkaku kicked at the dust, and Yachiru sighed deeply.

"But we're so much better!" She dropped her shoulders and head back. "He's pro'lly miserable."

"Y..." Ikkaku sighed. "Yeah." He turned and looked at the building again, the corner of gray visible through the green. "Bet that painted asshole won't let him go. Bet he needs rescuin'."

"I thought we asked Ol' Man Yama to send him back."

"We did." Ikkaku stuffed his hands in his pockets. "Nothin', yet. But there ain't nothing I can do about it." He kicked dust a few times, and Yachiru hummed and squinted at his face.

"You miss 'im. It's okay, y'know." Ikkaku winced his eyes shut, and Yachiru stuck her tongue out. "Only one thing to do." She jumped up and swiped his belt, loosening his shihakusho. "Come an' get me, Pachinko Head!"

"Hey! Yachiru!" He spared one last look at the SRDI compound in the distance, then gave chase, bolting after Yachiru and holding his kosode shut. "Get your shrimpy ass back here, or I swear to God, Yachiru..."

The SRDI was forgotten, for the moment. It just haunted Ikkaku, that someone could be so close but feel so far away.

Six weeks after leaving home (because make no mistake, he knew where his true home was), Yumichika got his first dose of pregnancy side effects. He was leading training exercises with the Twelfth Division's eleventh and twelfth squads, demonstrating a combination technique of hado and hakuda. He demonstrated a few times, then got a few of them to attack him so he could demonstrate a practical application. They just weren't getting it, though, and Yumichika was getting a headache.

"Alright, let's try it the hard way." He brandished his practice boken and took a wide stance. "I want ten of you punks, come at me! All directions! I don't care what you do, if you're doing this right, I don't need to look at'cha!" Ikkaku had egged the unseated Eleventh cadets on in just the same way, and the words felt good to say and hear. Almost made the headache go away. He could hear them taking position, and tensed. He could hear, feel, smell them coming. The field already smelled like sweat and iron, and then blood. That was weird. Nobody was bleeding yet.

The assault began, and Yumichika was ready. He sidestepped and dodged the first two, rapid-fired Sho along his right side to repel them while blocking on his left, then Haien to his left to reprove two there. He landed on his right leg to pivot, but when he spun around, readying Shakkaho with his right hand, something in his brain spun. His headache imploded, and his vision went black.

The next thing Yumichika new, he was hearing their voices, sniveling and weaselly, above him:

"Hey, does this mean we took down the Third Seat?"

"Temporary, anyway. Does it still count?"

"Hey." Yumichika was satisfied to discover his mouth still worked. "Listen up." The squad kids hovering over him jumped back when he sat up. "If an enemy is down, but they don't look like they should be dead, double-tap!" He thrust his hand out with a stab. "Make sure they stay do-" He moved his shoulder back, his head whirled again, and he passed flat out again.

The next time he woke up, it was with Nemu over him. "Third Seat Ayasegawa, your blood pressure dropped." Yumichika groaned as sensation washed back in degree by degree, and he could see an IV in his arm leading to a small pouch of clear fluid in Nemu's hand. He could also see that the training ground had been cleared. Nemu continued, as if completely certain he was listening. "You will need to remain more hydrated during exercise periods. However, this is entirely normal for your current stage in pregnancy."

"Oh. Sheesh." Yumichika wiped ice-cold sweat from his brow. "Renji never told me anything about his Captain just up and passing out. He just got angry and puked everywhere."

"He may not have passed out. Not every pregnancy is alike." The pouch emptied out, and Nemu carefully, efficiently pulled the IV needle from his arm and swiftly patched him up with a bit of gauze and some medical tape. "Your blood pressure will continually drop until about the midpoint of your pregnancy, and then rise. You will have to be careful with yourself."

"Guess so." He flexed his arm a little, and put his hand behind him to try and get up. Nemu reached out to stop him.

"I wouldn't yet-"

She was right, because the moment he got to his feet, nausea raced up through him and he dropped right back down to his knees and retched into the dirt. Nemu scooted around behind him and rubbed his back. Hell, his throat burned! He couldn't remember the last time he'd been physically ill. He was sure he'd taken a few gut hits that made him heave, but if he'd vomited then, the other pain in him must have overwhelmed the pain of this. Instead, he had to take a breath to get his composure before throwing some loose dirt onto the sad remains of his breakfast.

"Okay." He wiped his mouth on his sleeve, spat, and regretted it. Such a disgraceful thing to do, but there was something base in all this, wasn't there? It was an act of nature. Didn't change the facts: "That sucked." He brushed off his knees. "Nothing to do about it but rinse my mouth out and try to get on with my day, right?"

"I'm afraid that's what most mothers-to-be must do," Nemu confirmed somberly, and Yumichika trudged for the edge of the battlefield and grabbed his bottle of water and towel.

"Glad it's just paperwork this afternoon." He sighed, and forced a smile. "First time for everything. Guess it takes getting used to, right?" Nemu smiled back, a hint of warmth there, but not enough to ease Yumichika's mind or stomach.

Turned out, the first time would not be the last. Yumichika rejected lunch five minutes after finishing it, and had to go back and beg for a smaller portion so he didn't go completely hungry. He kept dinner down until he woke up the next morning and lost whatever hadn't been digested.

"Please," he pleaded down towards his midsection between heaves, "you'll starve if I starve."

He did a little research and experimentation (a little test and check, really but when in Rome, right?) to find out his first solution was probably the best- smaller meals. He would eat some of what he was given at the cafeteria and pack the rest away in napkins in his pockets to eat a few hours later. He also managed to dig up some ginger-lemon tea that soothed his stomach. He also discovered that when he felt lightheaded, he could stop a fainting spell with a long drink of water and two minutes of deep breathing. Not passing out at all was a nice way of avoiding the vomiting that followed. He still threw up in the mornings, but since his metabolism was speeding up to match his diet, he was digesting a little faster and wasn't expelling as much when he did. It was nice to know he was nourishing the baby, at least.

This only led to another problem: he was hungry.

His stomach made clear when it was empty, and it ached and twisted and made him feel nauseous all over again. He tried demanding seconds or extras at the mess hall, but was met with a blank stare no matter who was there. He tried to bring it up with Kurotsuchi during his next weekly check:

"I feel like I'm starving to death."

"Your caloric intake is adequate." Kurotsuchi didn't even look up from the notes he was taking, nor did his hand halt. "I'll be sure to give the Kitchen team instructions to adjust your diet as necessary."

"I'm hungry now." Yumichika ground his teeth together, and the next words exploded out of him: "Hell, it's like when I was starving as a kid! This fucking thing's got a reiatsu like a beast, and it wants food!" He swiped the thick gel off his stomach, already sour from another examination without seeing any of the "data" Kurotsuchi was collecting (or, as he considered it, "pictures of my baby") and his mood was worsening by the second. "Hell, from what I know about your Bankai, you got some experience with hungry babies."

"Oh, and how do you know about my Bankai?"

"Ishida told me when I was in Ka-" He stopped, because he heard tight, uncomfortable laughter from behind the sonogram machine, and looked to see Nemu stifling giggles. Kurotsuchi seemed to notice as well and cocked his head towards her with exasperation. Yumichika glanced to her too- had she ever made more than the tiniest squeak of "Yes sir" around the Captain before?

Nemu, knock-kneed under her "father's" stare, waved her hand in front of her face. "Sorry, sorry, only..." Her voice dropped to a faint whisper, clearly still choking back giggles. "Ashisogi Jizo getting hungry and tearing its way out of its mother... goodness, what would its mother-"

"Nemu, stifle your racket or I'll find new ways to plug your noisehole." Kurotsuchi closed his notebook with a snap, and her mouth snapped shut too as he turned his gaze back to Yumichika. "Ayasegawa, the entire division has been made aware of your condition. As such, they are all aware to treat you with an extra hint of care. Mind you, that is the only reason you have been treated as delicately as I have treated you." He closed in, teeth all too close to Yumichika's nose. "You are a test subject. Your Seat is a convenient cover for my ability to use you. You have no right to make demands of me. Are we clear?"

Kurotsuchi's breath was foul, like rock salt and dry mint barely covering the odor of rotting meat, and Yumichika felt compelled to retch. He held his breath just long enough to squeak out an answer. "Crystal."

Nemu helped Yumichika to his feet, and he bolted for the wastebasket behind the desk. Kurotsuchi scoffed and stepped over him, but Nemu patted his back as he ejected his most recent meal. "Are you going to be alright, Officer Ayasegawa?"

"Y-" He spat. "Yeah." He slumped onto his knees, and managed a weary smile. She put on a small smile right back, which quickly vanished, and he wiped his mouth off and spat again. "I don't know what he's brushing his teeth with, but it isn't working."

"Ancient Egyptian recipe he wanted to try," she answered automatically, then, "It's only five more weeks through the first trimester, and your nausea should wane." She stood up, and he matched her, getting up to his feet. "Captain Kurotsuchi said that once you're past the highest risk of losing the pregnancy, the experimentation will begin." She then whispered again. "I'll try to get you an extra snack between your meals. I've noticed you doing that."

"You're sweet, Lieutenant." He smiled at her, genuinely this time. It was occasionally difficult to believe she was Kurotsuchi's "daughter," from both the way he treated her and how very different she could be from him.

Kenpachi would never talk to Yachiru the way Kurotsuchi did to Nemu, nor (from what he'd heard) treat her with such calumny. If he was collapsing on the training grounds, the squad would probably at least go get Ikkaku. Ikkaku would... Ikkaku would...

No matter what Ikkaku would do, it would probably be better than this.