Summary: The realization that each passerby has a life as vivid and complex as your own is a scary one indeed.

Sonder

Heavens Arena Tower loomed over the hurrying figures on the street below, its lights bright and sparkling in the cold night. It was winter, a time for rejoice and relaxation. A time spent with loved ones.

Head and shoulders dusted by a light snow, a young assassin's flat blue shoes scuffed down the sidewalk below. His breath plumed in murky white clouds in front of his face, baggy black jeans and a baggy turquoise sweater hanging on his body. No hat or gloves. Couples on the streets turned to stare at the lone silver-haired boy in the darkened city. He was only six years old.

His hands remained stuck in his pockets as he sauntered forward. He noticed the people staring at him but hurried along. Raising a clenched fist, he was proud having finally completed the task his father had set before him two years ago. Finally reached level two-hundred! Silva had forbidden the boy to return home until he had reached the more formidable foes at the upper levels. It had been a long and hard ordeal, but he would be lying if he said the thrills of the Battle Arena weren't enough to keep him occupied during that time. No one had come to visit him during that time, as per his training. Not even his overprotective mother.

I wonder what Dad has planned for me next, he thought, his gaze surveying the street excitedly. He was startled to find colorful lights all around him. Laughter filled the air.

Taken aback, the young assassin stopped.

There was a certain cheer in the atmosphere that he hadn't noticed before… and suddenly, he became very aware of the whispers that circled him.

"Why is he out here all by himself?"

"I wonder if his parents know where he is…"

"Should we do something?"

Killua kept his head down as they brushed past, focusing instead on the snowflakes that fell in small piles around his freezing wet shoes. Heavens Arena grew smaller in the distance as he trudged along.

I don't belong here.

The thought was sudden and frightful. It surprised him, arrested his breathing, making his hands ball up tightly inside his sweater pockets.

Maybe he hadn't noticed it before because he'd been so focused on getting to the 200th level, but now he wondered… how couldn't he have?

Feeling the particularly intense sympathetic stare of a woman across the road, Killua halted again. When she leaned over to whisper something into the ear of her companion with a gloved hand to her mouth, his head snapped back to the sidewalk in a strange humiliation. He continued on quicker than before. He flushed, his ears reddening. He gritted his teeth.

Killua kept a quicker pace until he was on the edge of town. One hand on the frostbitten bark of a tree trunk, on an incline overlooking the city, Killua scanned the area below the tower. The colorful lights reflected in his aqua eyes.

What was that, all the joy he had felt around him?

~o=O=o~

Curious, Killua asked about the outside world – but the other Zoldycks wouldn't have it. They sensed the danger in this and increased his training tenfold. Killua wouldn't have time to think of such things and wonder what a "normal" life would entail. If he became distracted now, he would certainly never become the great assassin he was destined to be. Illumi overtook his training from then on, and Silva kept a peculiar distance from him. Killua only saw Silva during meals. He rarely met eyes with Killua, and when he did he never held his gaze long. It bewildered him, but Killua never said anything. If he hadn't known better, he would have said the look on his father's face was one of… guilt?

Only Zeno really stayed the same. They sat behind the manor after training, sharing candies and jeering at each other. He rarely saw his other siblings, save Illumi who was his teacher. They were all training – though Killua couldn't help that he was missing something that had been there before. No one said anything to make him catch onto the barest of thoughts and remember, and he didn't dare ask. He already had so little free time as it was with his current training schedule.

He grew accustomed to the stares he received while on missions that required him to be out in public. He understood them; he was a boy no older than seven, skulking the streets alone with dark eyes that had seen more violence than other people could hope to understand. The eyes of a killer. An assassin.

Killua had long since learned to think himself separate from other people. He couldn't expect anything from them. They were more often hindrances and targets than allies to his work.

Despite his intensive training, Illumi's and Kikyo's nonstop buzzing over his head, Silva's distance from him, Milluki's and Kalluto's absence from his life, Zeno's unchanged demeanor, the butlers' indifferent protectiveness over him... Killua barely felt anything at all. He enjoyed the rush of adrenaline when he completed a mission flawlessly, or when he murdered without fail. He panicked and cursed when complications arose. But something wasn't right, and he didn't know what. He didn't know why.

He escaped Illumi whenever he could, taking breaks behind the manor with Zeno, eating ChocoRobo with him – the candy he had come to love in Heavens Arena – or alone. Eventually, even the old man's jokes became jarring and uninteresting to him, as if they hid something else.

Missions were the only times Killua was allowed to leave the manor, and it was only to kill. Blood swam before his eyes in pools sometimes, yet he felt nothing. Only fatigue. If that.

He couldn't rest. The blockage in his mind wouldn't move, no matter how long he tossed and turned at night, wondering why that woman on the street near Heavens Arena had looked so worried, wondering what could have happened if he'd let her approach him…

Five years passed until he finally snapped.

Illumi was on a mission. Kikyo was berating him for slacking on his training, her hands on the exaggerated hips of her dress, lips thrashing wildly. Killua paid her little mind, staring blankly through the red light on her visor, the one she donned day and night. He couldn't help the arrogant superiority that he felt over her and other members of the family. Fickle woman. I could kill you right now if I wanted to.

Attracted to the sounds of drama, Milluki trotted by with a sort of hop to his step, trying to look casual. Any source of entertainment was well-worth it when one left the house as little as him. When Kikyo finished yowling at him, Killua said nothing, only stared at her with unamused, dead eyes. He hadn't been listening, so what would he even say?

After a few moments, listening only a few paces away, Milluki became more angered than his mother. "Brat, don't just stand there gawking at us! Answer mama!"

Killua turned toward Milluki, surprised by his loud tone. "Oh sorry, I wasn't listening."

"Kuh!" Milluki tightened his fists.

But Kikyo spoke first, a haste to her voice. "Killu, don't you realize how important it is to keep improving your skills? This affects all of us! You can't slack off if you want to inherit the Zoldyck throne!"

"Inherit the Zoldyck throne?" repeated Killua, incredulous. "How is that such an honor? Killing people day and night for money. Booo-ring. I do that now, and I'm bored out of my mind." He turned half away from them, arms at his sides.

A vein popped out on Milluki's head. He jutted a finger down at Killua. "You little shit! How dare you say that! I would give my life for this position, and you're just throwing it away!"

Killua answered swiftly, his voice calm, "We all know you care more about your video games than the family business, Milluki. It's not like you didn't have the chance before me."

Shocked by the disinterested matter-of-factness of Killua's voice, Milluki said nothing. After a moment, Kikyo spoke again – this time, her voice was chillingly soft. "Killu, you have to understand the impact our business has on the world. It's been in the family for generations, and your grandfather, who bore witness to his legendary father, Maha, and grandfather, Zzigg, was the one who declared your skill to be unlike any Zoldyck before. As a member of the family, it is your duty to upkeep the tradition and become the best assassin you can be. When disasters strike, it has always been the Zoldycks who have been relied on to quell those disasters, and receive great profit for it in the process. It's why we can live as well as we do!"

These undeniable truths spat at him from Kikyo finally struck a chord in Killua. He lurched forward. "Well maybe I don't care about any of that!" His fists shook. He found himself trembling. Then what do you care about? a voice asked. He gasped at the thought. The answer wouldn't come.

Kikyo was frozen by Killua's passionate cry, but Milluki had reached his limit. He swung a meaty fist. "You spoiled, ungrateful –!"

That was when Killua recalled the knife he'd taken outside. It was in his hand now, and his grip tightened on it. Milluki was an immediate threat.

He avoided his brother's wide, uncalculated swing easily, and used the created opening to duck under him and stick the knife in his side. Milluki screamed and doubled over, clutching his stomach. A few drops of bright red blood shone on the white tiles, which only further drove Killua into dissociation.

"Killu! What have you done?!"

He turned to his mother, who reached for him with her sharp, red fingernails. Another threat. Killua flexed a hand until claws stabbed from his fingertips. As she leaned down, he slashed her across the face, shattering her visor.

With them howling in his ears, Killua came back to reality. Violent obscenities spewed from Milluki's mouth as he pushed himself toward Killua, on hands and knees. His mother only screamed. He heard clattering footsteps in the halls up the stairs. The butlers were on their way.

Looking around, Killua made a decision.

He turned and ran.

The butlers could only guess at what happened, for there had never been an internal conflict in the Zoldyck Manor so violent before – members of the family didn't attack each other. They sent a message to all the butlers across the Zoldyck Estate to scour the grounds for an intruder.

When Milluki finally stopped howling long enough to tell them what had actually happened, Killua was long gone.

~o=O=o~

Running around corners and through back alleys, he traveled farther and farther from Kukuroo Mountain and the Republic of Padokea. He didn't stop even to eat, didn't rest for days. He was trained for this kind of deprivation after all.

Trained as an assassin. The only fact that had given him pride all his life was suddenly heavy and cold in his throat. So far away from his family, with no thought to return, he became aware of how big the world really was. Still many miles from the next town, and he'd been walking for five days without food and little water, he was reaching his physical limit. Only when he stumbled, looked up at the sky, did everything come crashing down on him.

I ran away from home, he realized. And even less triumphant, I have no one else in this world. Panic surged up inside him. What will I do? If he hadn't had an empty stomach, he may have retched right then. But Killua could only look up at the sky, mud on his hands, knees, and face. He could only wonder at the vastness of the stars he had seen so many times, yet never paid attention to before.

Wooziness overcame him with this in mind, and he pressed his forehead into the muddy ground.

At the next town, he found a place to eat. He hadn't brought any money, but his bank account was hefty in checks from his missions.

Well, maybe not – he did buy a lot of candy with it.

He was sure to withdraw cash from the ATM outside so it would be harder for his family to track him. The café was small and quaint, and the cashier was reluctant to serve a twelve-year-old boy alone this late at night, covered in grime, barely able to stand. He didn't act anything but tired though. He was used to this.

They only served pastries and beverages, so as he left, Killua bit into one of eight tortilla-shaped pastries he'd gotten: a chocolate filling wrapped in a crepe with powdered sugar on top. The other seven pastries were crammed in his pockets for afterward. No one else was on the street at this time. The white LEDs under the café's awnings cast his silhouette on the concrete sidewalk, the place's glittering red "OPEN" sign blinked on and off. It was getting chilly.

His body sighed in relief at the sugary nourishment as he savored the sweetness of the pastry. And again, Killua looked up at the sky. Murky clouds covered the distant stars.

Hearing footsteps, Killua hid in the alley behind the café. A strong presence appeared around the other side, and two men walked toward the door.

"The Hunter Exam was hard even for you?" he heard one of them say. "I wouldn't have guessed that. Usually you're raring to go when it comes to this kind of stuff."

The other man laughed heartily. "Yeah, well, this time I think I've hit my mark. They employed safety nets last year that they don't every year, and I would have died if not for that. I'm still an amateur hunter, so –"

The bell clanged as they entered, and the rest of their conversation was lost.

Hunter Exam? Killua had heard about the Hunter Association many times from Zeno and Silva. Hunters were said to be a group of vibrant, talented individuals who used their skills to specialize in whatever they pleased: protection, murder, anything. Those men said the exam was difficult. Killua had to admit, the one who said he participated had held a presence unlike most civilians he came across – even greater than his targets on missions.

The hairs on Killua's dirty arms stood on end, sweat mixing with his grime. If he could become a Hunter, wouldn't that make him one of the stronger few in the entire world? The challenge excited him – but the possibility of losing was what he was really looking for.

As the two men exited the café and waved their goodbyes, he stuffed the rest of the pastry down his throat and stepped out of the shadow of the alley, in front of the man who held the stronger presence.

The man blinked at Killua in surprise, a mocha in one hand. "Oh, hello."

"This Hunter Exam," said Killua, "where can I find more information about it?"

The man was a little wary, seeing how dirty Killua was and how he emerged from an alley, but grinned, catching the seriousness in Killua's eyes. "Your interest is admirable, but I wouldn't risk your life for it, kid." He bent down and rested a hand on Killua's shoulder. "The Hunter Exam isn't for drifters to take just for the kicks. You have to prepare for the challenge more than any –"

Killua's gaze hardened on him, and the man felt a pressure in the air around them. He lifted his hand from Killua's shoulder, stepped back. "Trust me. I'm prepared."

With the man staring after him, unnerved, Killua repeated the man's words in his mind. The location changes every year, so you'll find more information at the applicant headquarters. After that, you're on your own.

I'll find out what it takes to become a Hunter! Killua declared, downing the fourth pastry. He had to build up his strength.

Yeah. This should hold him over.

With any luck, I'll figure out what I want to do now, he thought absently, ignoring the gaping feeling inside him.

A dark voice pinged at the back of his mind.

Yeah, right.

~o=O=o~

Filled with the gasps of hundreds of men and women – 405, to be exact – the tunnel was dark and sweaty. He didn't know where they were going, but he was taking it easy. He hadn't forgotten his skateboard before his mad dash from the Zoldyck Estate. Man, this is boring…

"Hey! Wait up, kid!"

Killua turned toward the cranky voice, to a tall man with a stubbly chin. His blue dress suit was as large as he was. "Hm?"

"You should show the Hunter Exam some respect!"

Killua didn't get it. "What do you mean?"

"Why are you using a skateboard?!" the man cried passionately, pointing at him. "That's cheating!"

Killua looked down to his feet, then back up. "Why?" he asked honestly.

The man was taken aback by his unpretentious attitude. "This is an endurance test!"

"No, it isn't."

"Huh?!"

Behind the flustered man, the obscure bouncy black hair of a boy his size caught Killua's eye – his tacky green outfit, slightly vacant but determined expression, honey-colored skin, black hair, brown eyes.

"Gon, what are you saying?!" the man blurted.

"The examiner only told us to follow him."

"Whose side are you on, ah?!"

Killua leaned to direct his skateboard back, away from the old man. "Hey, how old are you?" he asked, his chin out. He wasn't sure why, but he was going to get an answer.

"I'm twelve years old," the boy answered, looking at him.

This startled him. Same age as me.

As the boy cocked a grin and one eyebrow at him, Killua felt something different. He wasn't sure what. An interest that he hadn't felt ever before? Maybe…

Yet it was more than a simple interest…

Small and fragile as it was, the feeling that gripped at him that day never could have prepared him for all that was to come. It blossomed into something irreplaceable and spellbinding. Not from the untouched brightness in Gon's eyes, though that was a part of it – but because Gon was the only person who looked at him without arrogance or sympathy. Only divine interest. For him.

When faced by unspeakable danger, Killua overcame. Not for himself. He never had fought for himself – for anyone – the way he fought for Gon…

Killua knew it: he would do anything for him. It was dangerous. It frightened him. Yet he didn't care.

Killua was tentative to accept Gon's interest, even jealous of how others were drawn to him, like moths to a flame. But he soon found that he didn't care about that either. Being able to share just a shred of that light was enough. He knew it from that first moment in the tunnel.

It was enough.

~o=O=o~

The streets were lively and colorful again, bustling with merchants, sailors, shoppers, and travelers. All around him people laughed and surveyed merchandise, walked listlessly to and fro, not a care in the world. This time, he was one of them.

With Alluka and Gon by his side, he could share in the merry flow of the streets. They bought sweets, toured, laughed, and joked. His little sister Alluka, forgotten by the mind-controlling needle Illumi had inflicted upon him, giggled at the flattery of the merchants and how Killua reacted to them, her face lighting up at each new item she set her eyes upon. Gon was absorbed in everything around them, as always, and eager to include Alluka in their adventure.

The world was warm and calm.

"The only reason we're both here today is thanks to the time I spent with you," Killua said, eyes bright, smile sincere.

"No, I should be thanking you!" Gon assured frantically, waving his hands in front of him.

But Killua's gaze faltered, which caught his friend's attention. He was always too honest. Killua always too dishonest.

Their roles had reversed now.

Conflict in his face, Gon huffed out, tearing his eyes away. "This is no good. If we stay here any longer…"

Killua closed his eyes, hands in his pockets. He knew what Gon wanted to say. He had often felt it himself these last two years. If I stay here any longer, I won't be able to stop myself. One day, he would tell Gon everything he had done for him – he would go into such excruciating detail that Gon's head would overheat and explode in that way it does when he can no longer sustain any information.

But here they were, about to separate, for who knows how long.

That day would have to wait.

"Yeah." Killua said it clearly. Regret touched his voice, but not because their coming separation. Circumstance called for it. It tugged at him and gave him hope all at once for something anew, for all the negativity and attachment of his past to be washed away, replaced by nothing but sincerity next time.

As Gon stood before him at the gate to the World Tree, this time, both of their faces were radiant – not just Gon's smile reflected back at Killua as it had in the darkness of the tunnel of the Hunter Exam. With Alluka at his side, Killua knew there was more than one reason to live.

Gon turned away, as did Killua, and he recalled what it had felt like to believe he was the only person in the world who needed a friend as much as he did…

To believe how far they had come from a stranger's warm gaze on a weary journey home.

This was originally posted under a separate fanfiction, but I decided it would be better that these two go together. I may continue with one-shots of other characters as I had planned to do on the other story as well if inspired~

I hope that you enjoyed my take on Killua's past, and that you will leave your thoughts below. Happy KilluGon Day!