Warning: Child Abuse, Death, Assassination, Zoldyck Family Shenanigans.

Disclaimer: Hunter X Hunter belongs to Yoshihiro Togashi, Shonen Jump, and Studio MADhouse.

Enjoy!

Killua Zoldyck's first birthday had been filled with both screams and silence.

His mother's screams had filled the room as she gave birth to her third baby. The birth was painful, yet successful, and she had given birth to a healthy baby boy.

The family's midwife had washed the blood and placenta off of the baby, revealing wisps of what looked to be pale hair. The midwife gave the crying baby to his mother.

Although Kikyou held her crying baby, she did not attempt to soothe or feed him. She had to set an example for her child. Assassins didn't show mercy or kindness to their targets, and the Zoldyck family were the best of the best. The assassins that came from the confines of Kukuroo mountain did their jobs efficiently, and this came from an almost intuitive knowledge of what an assassin's values were. A Zoldyck's training began at birth.

One minute later, Kikyou Zoldyck gave her son back to the midwife, and waited for her husband to come in. The baby's training started as soon as he was named.

Killua's fifth birthday had been the day of his first kill away from the Zoldyck estate.

His parents had tasked him to kill the young daughter of a crooked CEO, in order to remind the man of his debts to the mafia.

Killua's instructions had been simple. He was to use the window to sneak past the girl's security and into the girl's bedroom while she was sleeping, slit her throat, and leave the body in the girl's bed for her father to see. He would then leave the window open and dispose of the murder weapon by burying it in a nearby dumpster.

Although Killua knew the target's name, his brother Illumi had taught him to think of her as 'The Target.'

"It's better for assassins to not think of their targets as people," Illumi had said, and when Killua had asked why, Illumi simply replied that "If an assassin gets too attached to his target, he may forget to do his job." Killua had seen the logic in that, and nodded to show his brother that he understood.

This job was not first kill, nor would it be his last. The road to becoming the leader of the Zoldyck family of assassins was paved in corpses and blood.

Killua would not fail his job. He was destined for this. If he did fail, his family would send him to the disciplining room, punishing him severely. He would not fail. He could not fail.

After saying goodbye to his sister Alluka, Killua and his eldest brother boarded one of his family's private airships. At eight clock in the local time, the sun was setting. At nine o'clock, Killua was waving at his brother, a sharpened knife hidden in his coat pocket. He followed the signs that led out of the airport, and began following the directions he had memorized to the target's house.

At ten o'clock at night, Killua was standing over the sleeping figure of his target.

The girl - no, Killua reminded himself - the target didn't seem to be too much older than Killua himself. Then why did it matter? Why was Killua having so much trouble getting himself to finish the job? Killua was risking punishment from his family just because his target was in his relative age group. Killua wasn't so stupid as to let let silly thoughts hinder his missions.

With this thought, Killua took the knife from his pocket, and swiftly slit the sleeping girl's throat.

Taking a shaky breath, the boy stepped away from the body and slid through the open window, stealthily making his way towards his brother and back to his family's stiff, awkward praise.

At the tender age of six, Killua had already fought his way through almost 100 of the floors at the Heaven's Arena. It didn't matter whether he was six or seven, after all, his opponents would still keep underestimating him as long as he looked young enough, despite his fearsome reputation.

More importantly, Killua doubted that one's enjoyment of sweets and the other joys in life depended on age.

Killua's tenth birthday was filled with a restless yearning for escaping the confines of the Zoldyck estate. To put it simply, he was bored and he wanted chocolate. The last time the young assassin had been let out of the house had been weeks ago, when his parents sent him out for a job. Killua hadn't had chocolate for over a month, before his mother had ordered the butlers to do something about his hidden chocolate stash.

On Killua's tenth birthday, he had slipped away from his family's estate in order to buy a chocolate bar in the neighboring town. On that same day, Killua had been caught by his family.

Here's how his failure went: Killua had successfully slipped past the security surrounding the mansion. The young assassin had made it to the neighboring town, and had just finished paying for a chocolate bar when he ran into his mother's butler Gotoh, who had just finished buying a local specialty ingredient for his mistress. The butler knew him on sight, and took him back to the family estate.

Killua remembered his failure. He remembered Gotoh's firm grip as he dragged the boy towards the butler's quarters. He remembered his mother's nails digging into his arm as she took him to the disciplining room. Most vividly of all, however, he remembered the cool feel of chains, the stinging of lightning and whips, and the smell of blood and electricity.

Sometime before his twelfth birthday, Killua found himself back at Heaven's arena. This time, however, he was accompanied by his friend Gon. The energetic boy had fully uncovered Killua's rebellious side, turning the seeds of rebellion against his family's teachings into a fully-fledged bloom. Killua would be eternally grateful to Gon for freeing him from his family.

Since the boys had both cleared the 200th floor, they were required to sign up for a fight every month.

"I'll sign up for May 29th," Killua had said one day, "Since it's my birthday."

"Really?" asked Gon excitedly.

"No." Killua replied.

"Then when is it? I know you've told me before today..."

"Why should I tell you?"

"Because birthdays are important, and should be celebrated!"

"I already know that, dummy," Killua interrupted, "Just because I was raised to be an assassin doesn't mean I lived under a rock. I did give you that choco-robo for your birthday, remember?"

"Yeah," Gon said, "but I did see you buying it from the vending machine after Zushi and Wing-sensei gave me their gifts…"

Killua looked away from his spiky-haired friend, but before he could say anything, Gon spoke up.

"It's okay, Killua," Gon said, putting his hand on Killua's shoulder. Killua stiffened at the touch. Even after traveling with Gon for half a year, he wasn't used to friendly touches.

"I'm just a little surprised, that's all. I'm not mad at you for not knowing about birthday presents."

Killua shrugged out of Gon's touch, before making himself seem as indifferent as possible. "I've just never received any Birthday Presents, that's all. I didn't realize that they were normal."

Gon looked shocked. "REALLY?" he all but shouted.

Killua shrugged with indifference, showing no hints of any other emotion.

Gon scowled, and then looked straight at his friend. "Then I'm going to give you the best present ever!"

Killua blushed slightly, but appeared thoughtful. He then looked at his friend.

"Baka, how are you supposed to give me a present when you don't remember when my birthday is?"

Gon pouted, and said something about how he did remember, and Killua howled with laughter at his friend's expression. He knew Gon wouldn't forget something so important if it concerned one of his friends.

True to his word, Gon gave Killua the best gift known to man.

On Killua's twelfth birthday, he received a large box of fine chocolate, and an even larger box of choco-robos. Gon also reminded him not to eat all of the chocolate in a day, and Killua pretended to listen. If he could deal with most lethal poisons as if they were nothing, then he could definitely stomach malnutrition for a day.

However, Killua wasn't expecting the other presents.

Alongside Gon's present, he had received a birthday card from Kurapika, who had written that they had learnt of his birthday by looking through his Heaven's Arena stats on the Hunter Site. Killua felt thankful towards the non-binary hunter, and moved on to the rest of his presents.

Leorio had sent an authentic, hand-woven bracelet from his home country, and a first aid kit, complete with extra wet wipes. The medical student wrote in his card that "You should probably wipe off your hands off next time you're finished ripping out someone's heart. Not doing that is just plain gross."

Upon reading this statement, Killua scowled at the card and shoved Leorio's gifts aside.

He had even received things from his acquaintances. Chairman Netero sent him a cheap card(the old man had probably gone senile, why send a card when the recipient wasn't even a hunter?)

Hisoka had sent a deck of cards that Killua promptly threw away. Did Hisoka see a need to curry favor with Killua due to the fact Gon was going to fight the perverted clown in just three short days? Killua didn't know and didn't care.

Lastly, Wing and Zushi gave Killua a gift card to a restaurant chain that was based in Yorknew. Killua supposed that they had heard from Gon that they were planning to go there, and that the card would come in handy.

After spending the rest of the day training, Gon treated Killua to a celebratory dinner at one of the local restaurants.

The boys walked towards their rooms at Heaven's Arena with full stomachs and sleepy smiles on their faces.

"So," Gon said, "What did you think of today? "

Killua looked at Gon and gave the spiky-haired boy a genuine, cat-like smile.

"This is the best birthday that I've ever had."

End

I'm such a slacker. It's been a week since Killua's birthday and I only release this fic now?

Lord have mercy on my soul.

Thanks for reading!