A/N: I've been thinking a lot about character development lately, especially for the Zoldick siblings. For example, they all (we presume) underwent more or less the same training and had the same childhood (based around the training), I have to wonder where the difference between Illumi and Killua really comes from.
For example, Killua had one/two younger brothers to interact with, not to mention Kanaria, and older brothers (Illumi was supposed to care about him, according to Biske)... also I have the feeling he was spoiled as a child (as much as an assassin can be spoiled) because of his talent, an idea that Milluki's comments supported.
Illumi on the other hand had no siblings for the majority of his life (Milluki is 7 years younger than him) and combined with the possibility that Silva and Kikyou didn't intend to have more children he might have been the only expected heir to the Zoldick legacy, which would be pretty pressure-charged.

Anyway, sorry about that...

Illumi does some experimental training, which changes his perspective a little.

Wake Up Call

It was another isolation room session, and it started as it always did: Grandfather gave him a shirt and shorts to wear, a bottle of water and box of biscuits, and then they walked to the basement and the familiar metal door in the wall. Illumi took it as he always did, stotically, stumbling into the room and sitting down against the wall across from the door, staring forward blankly. His knees were drawn up and his arms rested against them, because he felt warmer that way.

The isolation room was always cold.

For the first week, he sat quietly in the exact same spot for exactly 12 hours a day, and then lay down and slept for the same period, lying flat on his back on the floor. After a little while, that spot had started to get warm from the absorbed body heat, and now he felt better there than anywhere else. He slept without movement or sound, still as a statue, just like he'd been taught.

The second week dawned and Illumi counted it because he counted every hour, without pause, the words 'it is 5 o'clock', 'it is 6 o'clock' chiming in his mind every 60 minutes. When he woke, the first thing he did was go to the bathroom in the little slot in the corner, and drink the water that had been left for him. Illumi didn't starve, there were biscuits in a box that he measured out precisely to always have the same amount, once a day.

The third week saw Illumi restless. He didn't move from his position across from the door, but his hand tapped his elbow soundlessly, and his eyes blinked to a slow rhythm he heard in his mind.

Illumi had never been in the isolation room for longer than three weeks, and he didn't know how long this would last. His biscuits ran out after one month because that was how long he'd counted on as a maximum. Grandfather never told him how long he was going to be kept in there, because he said it would be counterproductive for him to anticipate being released.

The fourth week, Illumi cut his daily rations in half, and then in half again on Wednesday. He drank water once every two days, but reluctantly increased that to three. On Wednesday he did something he hadn't done since he was first introduced to the isolation room and walked around, carefully measuring his steps around the parameter of the room, counting 38 in total. Then he sat down.

On the fifth week, Illumi didn't cut the rations again and so they ran out that Sunday. His water lasted until Monday and then also ran out. He forced himself not to pace the parameter again because that would be wasting energy. He tried to go into a meditation, lying on the floor so as to conserve as much strength as possible, but it wasn't very successful. Eventually, his mind went back to what it was always like in isolation.

…

'It is 8 o'clock.'

On Tuesday, he didn't sit up when he woke and lay on the floor all day, occasionally shifting from side to side to preserve sore muscles. He stared at the ceiling and counted dots he hadn't noticed before, precisely one per second so that when he reacted 3,600 he knew an hour had passed. He kept counting and recounting dots until he fell asleep, and when he woke up he felt disoriented. He had lost his sense of time and so the voice in his head simply switched to '1 hour has passed', '2 hours have passed'.

On Wednesday Illumi had a thought that didn't involve the time. The voice in his head said; 'Is grandfather coming?' instead of '21 hours have passed'. He immediately went back to the former rhythm, but it was now impossible to recapture. The thought continued along that same line, repeating every minute until he wanted to hear a sound, any sound, to drive it away.

'Will grandfather let me out?'

…

58.

59.

60.

'Will grandfather bring more food?'

…

58.

59.

60.

'Has grandfather forgotten me?'

…

58.

59.

60.

'Is grandfather watching me?'

…

58.

59.

60.

'Does grandfather want me to die?'

He couldn't sleep that day, or that night. Illumi's time sense had become hopelessly tangled and when he closed his eyes, deciding it was night, he thought he heard the sound of footsteps outside. Listening for the imagined noise kept him awake and alert, senses straining, until he marked it roughly as being Thursday.

Illumi ate the box. He had sat there, staring at the cardboard for hours before he could bring himself to do it. The effects of starvation were beginning to make him dizzy, and when he finally got up and walked over to pick up the empty box of biscuits, he had to stop and lean against the wall, unable to coordinate himself enough to move. Things went invisible, for a moment, and he could feel an odd, tingling numbness. His vision exploded into something not quite black or white, a strange grey that he had never thought existed, although in a way he could still see the outlines of the room. Eventually it faded and he continued moving, ignoring the occasional uncontrollable shudder.

When he finally grabbed the box and practically ran back to his place across from the door, falling over and hitting his nose in the process, Illumi had to convince himself to do it. It was embarrassing, awkward, and he wondered if he wouldn't be poisoned from it. Surely, though, cardboard couldn't be much worse than other things he had been forced to ingest.

Finally, he ate it. Illumi carefully detached thin strips of brown packaging and put them in his mouth, choking on them until tears unwillingly stung his eyes. He forced himself to swallow, thinking for a moment that the half-chewed, soggy cardboard would stick in his throat and choke him. When it went down smoothly and left behind only a bland, disgusting aftertaste, Illumi took a deep breath before starting on the rest of the box. He finished it all in one sitting, eventually getting so used to the taste of cardboard that he no longer cared about anything except satisfying his hunger.

When he was finished, the thought of eating the empty water bottle also crossed his mind, but he soon realized that he couldn't chew the plastic.

Throughout the day, Illumi strained to hear the sound of footsteps coming to get him.

That afternoon, he took his shirt off and put it around his head to block out the sound, uncharacteristically turning on his side, away from the door, to sleep. He woke up with the thought 'Does grandfather want to kill me?' in his mind, and immediately started counting the dots on the ceiling to establish some sort of time. However, the numbers became jumbled in his head, one coming too slow and then several rushing by to compensate. Realizing he was no longer capable of precise time-keeping, Illumi propped himself against the metal wall and stared at the door, trying to block out his thoughts. Usually he never thought anything in isolation except the count of the hours.

Panicked, he tried to recapture the time, forcing himself not to think. It only made the thoughts in his mind more pronounced, and his head hurt. The migraine lasted for hours, that sort of pain that he could deal with normally, but combined with the thoughts that still wouldn't leave and the inexplicable feeling that he was dying, it seemed to turn into some brand new form of torture that Illumi had never imagined possible. Finally, he drifted off, more likely too exhausted to stay conscious than truly sleepy. Some part of Friday disappeared in a blur, and later Illumi could never decide how long he had been out for.

Marking it as Saturday, Illumi realized he hadn't had water in days and tried to stumble towards the bottle to make sure there wasn't any more, but found he could barely move. Frightened of the loss of his mobility, Illumi lurched himself up with all the energy he could muster and stumbled across the room to the door, irrationally thinking he heard footsteps against the hollow metal floors of the basement level. For some time the dizziness returned and he was left on his knees, feeling as if he were about to slide off the floor. His own breathing became too loud when he pressed his ear against the door to listen. The thought that he had been forgotten became paramount.

"Grandfather?" Illumi had never, ever spoken out loud in isolation, especially not to call out to anyone. He was confused by his own actions, but the thirst had become a driving force and he said it louder again,

"Grandfather?"

'Did everyone forget me?'

"Grandfather!" The scream wasn't much of a scream because Illumi was unaccustomed to raising his voice, and because his throat felt incredibly sore. Nevertheless, he continued screaming, forcing himself to be as loud as possible. The room had concrete between the sheets of dull metal that made up the walls and door, so Illumi had to make himself heard as much as possible while his throat was still working. He kept screaming, switching from grandfather to father to mother to let me out without noticing, until the next scream came out a cough and he was reduced to hammering on the door.

Eventually he passed out. When he woke again, Irumi didn't know what day it was anymore, not even roughly. He assumed it was Sunday, when it fact it was Monday, and tried to get to the door again, thinking he must have heard something. His legs shook and his arms had to support him while he crawled across the room. Hunger and thirst were just types of pain and he had been prepared against, but the weakness that came with them frightened him. Illumi hammered on the door uselessly for hours, leaving his good arm bleeding. He tried to cry out again and realized his voice hadn't come back.

He stayed awake for three hours, then fell asleep without noticing it, propped up against he door.

Illumi woke on Tuesday and realized he couldn't move. The first thought he had was that he was going to die. It was the first time he had ever believed that his family was quite willing to kill him, but the thought felt very simple and true. The second thought he had was that he had to get out of the room at any cost, so Illumi turned over from where he'd slumped on the floor by the door and pulled himself up shakily, and then crashed against the metal with all the force he could muster. He continued to do this until his shoulder was bloodied and he fell down again, but there was a dent in the metal plating on the door and he smiled a mad grin at it before passing out.

The next time he woke up he didn't think, only crashed against the door with all his strength, hearing bones snap and turning over against the door to keep going with his other shoulder. He kept hammering at the exact same spot until he broke through to the cement underneath and then he kept going until he passed out, dropping on the floor in a boneless heap, ready to die.

The next time he woke up, he was being carried by his grandfather. Not understanding the situation, Illumi kept hammering against steel muscles, thrashing until his limbs trembled and refused to move, somehow trying to scream let me out without knowing why. His grandfather didn't acknowledge him and in a few moments he passed out again.

He woke in his bed, staring at the familiar ceiling. Illumi felt tired, unusually so. It was not the true, endless exhaustion that said he'd been training, rather the feeling was more like an inability to move, muscles incapable of responding to commands, arms too heavy to lift, although he didn't feel as if he'd been working out…

There were noises, too, the sound of birds outside, from the open window. The curtains tossing in a breeze. A steady beep of some machine nearby. Illumi did not feel the need to investigate, content to lie there in his bed. Normally he would have to get up and at least go to breakfast or lunch, or read, or work on his academics. Right now, though, he didn't think he could even lift a pen, his arm wasn't even responding to his commands. He could feel it, sort of, but the feeling was muffled. He wondered if he weren't drugged, if they hadn't overdosed him by accident again…

Thoughts of what training he'd had scuttled past, none of them entirely coherent. His mind rushed after them, trying to pin down what had actually happened.

Dinner with the family. Grandfather had been talking about Illumi's training at the dinner table. Mama had gotten angry about something again, father was as usually quiet. After that there was…

Illumi didn't quite remember that part, or how he'd ended up here in his bedroom in pajamas and tucked into bed. His head felt strangely empty, as did his stomach. When he tried to lift his head to examine his surroundings he realized both his shoulders were bandaged.

The bandages were the ones that tipped him off. Illumi remembered feeling blood flowing down his arm, one fist so slippery with it he couldn't grasp anything by which to pull himself up. After that, the remaining memory came quickly, like flashes of light across his vision, a whole month-full of thoughts and questions and finally something he vaguely recognized as desperation.

Most of all, Illumi remembered the distinct impression that he had been put into the isolation chamber not just for training or even punishment, but to slowly starve to death. He turned this thought over in his mind, toying with the idea, and realized it was illogical. He was not dead, in fact he seemed to have been taken care of after all. Obviously someone had come down to let him out and even take the time to bring him upstairs and put him to bed. When he examined the room around him, Illumi realized he'd actually been hooked up to an IV stand. Obviously he was not supposed to die.

Perfectly logical. Illumi had always appreciated thinking calmly, rationally. He could not understand why the obvious evidence that he'd been wrong didn't make the idea any less real to him. After all, if his parents had wanted to kill him there were certainly better ways to do it, and even if they wanted to torture him first this wasn't a particularly good method.

This explanation didn't so much ease his mind as make him realize how little punishment really differed from death. Illumi had always, always accepted punishment for misbehavior as something that was inevitable and well-deserved, like a part of his training against pain. He had never, until now, considered that his parents could go that extra distance and simply let him die instead of stopping at some point. It might have been the vestiges of childhood which had erected an unmistakable difference between punishment, which would eventually end, and torture, which would end when his life did.

The more he thought about it, however, the clearer it became to Illumi that he had been illogical, behaving childishly. He was an assassin in the business of killing people. Of course his parents would not hesitate to kill him if it became necessary.

Until now, Illumi had had a very clear distinction between his job and his family life. Being a killer had simply seemed like a faraway dream, the outside world where he would eventually go to commit murder was always outside, far removed from his family. He had retained the thought that the Zaoldyecks were separate from other human beings, isolated from their prey, living in a little bubble of safety where even the most dangerous training methods were always not quite torture, just short of murder.

To have that bubble burst so suddenly was, Illumi realized, more than a little… disheartening. He spent a few long hours blinking slowly at the ceiling of his room, frowning. After a while his eyes began to burn in a strange way and before long he realized that meant that he'd be crying soon. Ashamed of himself, Illumi rubbed at his eyes and blinked the tears away before they could spill, but the sinking, tightening feeling in his stomach stayed. He started breathing deeply, and the unfamiliar reaction went away soon enough.

He spent hours lying like this, mind mostly blank. Automatically, he had started counting the hours in his mind. It was a habit he had picked up before Illumi could clearly remember, and it calmed him a little to know that he could do it properly again.

Eventually the thought came that he had not been killed, and so it was silly to get all upset about it. Illumi had, obviously, done something right to deserve to be saved. His parents still needed him. They wouldn't kill him, of course. He was their only child. They still needed him around. He had obviously been doing well, since he was still alive. He was useful. Father needed an heir, and he only had one for now, and Illumi was it. They wouldn't kill him, of course, even if they could and had come that close.

And even if they had more children like mama was always talking about (all those conversations about mama wanting a little girl suddenly took on an ominous meaning) Illumi would still be eldest. He'd just have to be the best possible son they could ask for.

The thought, although not particularly happy, was at least calming. It was good to know that he was not going to be suddenly disposed of. A good, logical idea. A sold plan. Yes. Very good. Very…

The tears did come that time, and Illumi tried to wipe them away but they came anyway so he did what he used to do when he was little, hiding behind the long hair and his hands until it went away. There was no one in the room, which made him feel marginally better, but he was already behaving poorly for the perfect eldest son he was supposed to be, which made him want to cry more. Instead he breathed deeply and wiped the tears away, swearing that was the last time. He had never really cried before, at least not for no real reason, and this was definitely the worst time to start.

Instead, he decided to stop lying around, get up and start working on his academics while he healed enough to resume training. He'd have to show everyone he could do better. With that in mind he started struggling to sit, then stand, and finally look around to find his discarded books exactly where he'd left them, on the table across the room. Illumi managed two steps before the IV needle protested, and then he had to lean on the wall while he pulled it out, feeling sick and dizzy. He wondered if he shouldn't be hungry, but realized he really, really wasn't. Instead he dragged his history textbook and notebook back to his bed and collapsed on it, lying still for long moments until the room re-aligned itself and then starting to read from where he'd left off his previous lesson.

For a long time he couldn't manage to really understand what he was reading, the words just didn't seem to mean that much to him. Often he wondered where his family had gotten to, if they weren't going to come and check on him. Illumi realized he hadn't seen anyone, not even the servants, for nearly half the day now.

He had finally gotten seriously into his studies, memorizing names and dates, when his father strode past his room and stopped by the open door, raising an eyebrow at the scene. Illumi (who had of course realized his father was coming while he was still out of sight) wondered if that was a disappointed expression or not. Despite his conviction to be absolutely indispensable, he found he couldn't muster up the urge to care what his father thought anymore.

"You woke up, then?" Father walked into the room, sitting on the bed and casually examining the textbook Illumi had been reading, "How are you feeling?"

For a moment, Illumi had the urge to throw a temper tantrum and say he was feeling terrible, that he was going to be sick just to spite them all and he never wanted to see his parents again and he hoped they all died. Then he realized that it was pointless and childish, so instead he said "Fine." and went back to reading, not quite knowing what else there was to add.

Apparently, his father didn't know either, because after waiting for a few moments, he patted Illumi's blanket-covered knees and got up to leave.

END

A/N: A bit long for a character study, I guess. The subject makes it boring. I drew this up as actually more of an explanation for Illumi's behavior rather than a fanfic in its own right… the writing is secondary to the action and the characterization behind it.

Just to place it in the universe for you guys... afterwards I've always thought that Silva had that type of training canceled, considering that Illumi changed personality-wise because of it, probably more than Silva was comfortable with. My idea was that Zeno was the one to train Illumi (and have this idea), having more experience, while Silva trained Milluki and then Illumi trained Killua, etc. To me it seems more likely for Zeno to come up with something like this than Silva, who isn't as direct in his manipulations and seems to understand his children more than Zeno does.
Just a little blurb, feel free to diregard... (most of you probably don't bother reading this).

EDIT: A shout out to Allusho, a reviewer who has taken the time to give this fic a goodlook-over, to which I'm endlessly grateful. This is the sort of review I really appriciate, and hope to one day be able to give myself. It has helped me better my fic, and made me think of other aspects that could use some work. Thank you.