"Focus on the cup Leorio. Use your nen on the water."

Illumi had been brutally effective with Leorio's nen training, as his father had requested. From his ten used before surgery, to quickly learning zetsu, an ability he made use of a bit too often to surprise Illumi's younger siblings. Ren took a bit longer, only fully activating when Milluki had been more than a little bratty. Accidental it may have been, it was still amusing progress.

It was with his recent awakening of hatsu that encouraged Illumi to see what nen was natural to Leorio. They could work on the more advanced techniques later. He was curious what sort of nen Leorio wielded. Determined like an enhancer, short tempered like an emitter or perhaps the argumentative logic of a manipulator.

The three types of nen Illumi was certain he'd have one of them.

It was his own curiosity that needed to be sated. With a chance of a fellow manipulator in the house, it was best to know early on.

He watched Leorio's hands nearly touch the cup filled with water, a leaf floating innocently on top. He watched for any movement from the leaf or any change in the water.

"Hey Old Man!"

Leorio lost his focus, irritating Illumi as Killua jumped on Leorio's back.

"Gah! Killua!"

"Hey Leorio," Killua chuckled, a grin plastered on his face.

"What did you do Killua?"

"Aw. Why do you assume I've done anything?"

"Because it's tuesday and I haven't heard your mother weeping yet."

Killua gave a knowing smirk at Leorio's comment. It wouldn't be a normal week if he hadn't done something to make his mother weep yet.

"Killua, if you aren't hurt, you should leave," Illumi stated dryly. "Leorio is learning."

"Learning what? How to drink from a cup?" Killua asked as he snatched the cup. The water sloshed around inside the full cup and the leaf floated around, nearly falling out. Illumi snatched the cup from Killua's hand, not letting a single drop spill.

"It is a matter for older individuals Kill. You're too young to understand," Illumi brushed off. Killua plopped down next to Leorio, defiance clear on his face.

"I'm smart enough to understand whatever you're teaching him," Killua gloated. Illumi used a small amount of ren to try and scare Killua away. He felt Leorio's ten flare aggressively at the sudden nen usage, and his arm darted in front of Killua in a protective gesture. Illumi watched Killua's face go from fear, to shock, to content, then confusion. With In active, he saw how Leorio's ten almost seemed to wrap around Killua from his arm, creating a makeshift shield.

He relaxed his ren and saw Killua relax a touch. Leorio dropped his arm, but his ten remained constant.

"Killua, leave."

Killua grumbled and stood. He appeared irritated as he skulked off. Illumi refocused on Leorio.

"Now, let's try this again," Illumi calmly stated as he placed the cup before Leorio. The young doctor to be sighed and placed his hands on either side of the cup and focused his nen. He didn't know what he was doing, or what was supposed to happen. But he followed the orders of the eldest son.

"Stop."

Leorio held back a sigh but did as he was told.

"Look closely at the water."

Leorio looked at the water. It didn't seem out of place. It was water with a leaf on top. The shadows tinting it a somewhat slightly brown hue.

"That shift in color was from your nen. You appear to be an Emitter."

"Thanks?"

Illumi stared at the water with intense focus. Emitters were common enough, though few gave thought to the colors that varied from person to person within the cup. Brown though. So unassuming. So common. So easily blend into the world around. But it was more than that. In his travels he had seen brown paired with practically any color, so would he be that wY as well, potentially getting along with anyone with enough time?

He had already succeeded with his mother...

Brown is viewed friendly yet serious, down-to-earth color that relates to security, protection, comfort and material wealth. All things he could easily see in Leorio. It was almost unnatural how well the color under scrutiny fit their doctor to be.

Time passed without much thought. Too busy in training both under the butlers and Illumi to truly pay much attention to the passage of time except in fleeting moments. His forced learning of nen by the hand of Illumi had been scary enough to forget certain passages of time. Namely his own birthday, something Killua was determined to find.

Upon turning seventeen, he was considered "complete" in his training. He was to go and prove his skills by attending classes and become a legal doctor. Afterwards, there was a silent wager. Being now welcomed to the home by both parents of the Zoldyck children made him a desireable addition to their staff. Therefore, they would no doubt try to whisk him away.

Leorio decided he wouldn't go down without a fight on the matter. This was his only chance at freedom and he would do all he could to sieze it.

"I don't see why you have to leave old man," Killua commented sourly as Leorio packed his belongings in his briefcase. Killua didn't know how he could fit as much as he did inside the case, but assumed it was a butler thing.

"Because if I want to be a legal doctor, I need to prove to a medical board that I am capable to do what they ask. Be it a surgeon or general practitioner."

"Are those really any different?" Killua grumbled.

"Immensely. Most doctors are specialists in one field. It takes a lot of study just to prove acceptable in any study of medicine."

"And which ones are you doing?"

"Emergency work including surgeries, hopefully become a family practitioner as well, and should do well with pediatrics."

"Seriously?"

"It should."

"You sound crazy."

"Gee, thanks Killua. I'll remember that when I get my doctorates."

"You better you crazy old man."

"I am not old!" Leorio yelled. Killua laughed at the predictable response.

Leorio proved intelligent in his classes, his first hand experience and training on Kukuroo Mountain made him far more prepared than any of the teachers could have predicted. Especially how he was learning more than one area of medicine.

Many were amazed, more were envious, although a few were bitter about a boy who appeared from thin air besting others who had been born from families of doctors. Those were the ones that made Leorio actually thank Illumi for the aggressive Nen teaching. It helped picking up on their attempts to sabotage his work.

He hoped people who were trying to learn to heal would be above such tactics. Clearly, he was optimistically wrong.

Near the end of his rather accelerated schooling he took a planned semester off for a different kind of test.

With a grin on his face, he made his way towards one Zaban city.

So, I have gotten a few comments about possible shipping in this story. I currently have no end goal in mind with romance and am looking at what happens organically with writing. That being said, make of what happens as you will. As for the color thing, we only know that the water changes color, but realistically the type of color should vary. So I looked at psychology and colors and found this www . empower - yourself - with - color - psychology . c-o-m /meaning -of- colors . html

Get rid of the spaces and the dashes in com and you'll see.

And I am not a doctor so just a skip over his school just like in the manga and anime. Who wants to see Leorio take the hunter exam?