There you were, lying on your back with your arms spread wide, drenched in your own sweat. Quick and heavy pants were all that can be heard from you. Desperately, you tried to get up once more and try again. However, your extreme exhaustion prevented you from moving a single muscle.

You tiredly look at the ceiling, trying to stabilize your breathing once more. Eventually, you see Killua enter your field of vision, a slightly disappointed look on his face as he puts his hands on his hips.

"It hasn't even been 30 minutes yet, and you're already tired? I don't even have a scratch on me," he sighs deeply, looking down at your tired form.

"Are you... serious?!" You say, desperately struggling to speak properly. "I almost got you, like, 4 times..."

"Yeah, but you didn't, and I'm not even tired," he states matter-of-factly.

"Dammit... I give up," you say, slowly closing your eyes and accepting defeat.

Killua sighs once more. Stepping closer, he slips one arm under your knees and the other under your neck. You open your eyes in surprise at the sudden contact.

"Wh-What are you doing?!" you ask, a blush rising to your face as he effortlessly carries you.

"Getting you out of the way so Alluka can have her turn, what else?" he says casually, bringing you over to the corner of the room. He gently sets you down, letting you lean on the wall.

"Just rest here," he says briskly, though you didn't miss the way he smiled warmly at you.

You return a small smile to him, mumbling a quick, "Okay."

Killua didn't even go easy on Alluka, much to your surprise. In just under five minutes, she was already panting excessively, with one knee on the ground.

"I can't do it anymore... Onii-chan," she manages to say. You see Killua's eyes soften for the slightest moment, before hardening again to a strict gaze. He sighs. "Alright, alright," he walks over to Alluka, helping her stand. He brings her over to your side.

"Well, we have a long way to go," he starts, giving the two of you stern gazes.

"(Y/N), you're pretty fast and strong compared to the average human, but you leave way too many openings. We're gonna have to work on your stance first and move forward from there," he explains. You nod.

Then he turns to Alluka, who was already sweatdropping, anticipating the worst. He sighed heavily once more, "I don't think I need to explain this, Alluka... we need to start from the very beginning..."

"Y-Yes..." Alluka said, smiling sheepishly.

_ _ _

A few days later, you see Alluka sitting quietly by herself. Her eyes were shut, yet she seemed relaxed and had a very straight posture. Curious, you walk over to her.

"Alluka?" You call, poking her lightly.

"Hm..? Onee-chan?" Alluka replies, fluttering her eyes open and turning her head to you.

"What are you doing?"

Her eyes lit up at your question. "Oh! Remember when Wing-san mentioned the other 'Nen' a few days ago?" Asks Alluka excitedly. You frown a little, tilting your head to the right as you remember. "Oh yeah! What about it?"

She giggles. "Did you know? The other 'Nen' has a whole other meaning! It's not about aura but the force of our will! Even the four principles are the same, and that's what I'm doing right now! I'm doing the other 'Ten'."

You had a visibly confused expression on her face. "The force of will...?"

"Oh. I remember that," said a familiar voice from behind you. You look back and see Killua standing nearby. "It's what Gon and I did every day when he was injured in Heavens Arena."

"Oh? What does it do?" You ask.

"Hm... I heard its to help people get in tune with their aura better. It even helped smooth our Ten."

"Whaaat? Why can't I do that then?"

He sweatdropped. "Well, doing the actual Ten is better than doing the other 'Ten' anyways,"

You stare at him blankly for a while, processing his words, "Oh."

"Killua's right, (Y/N)," Wing appeared, with Zushi by his side. "The other 'Nen' should assist Alluka in opening her aura nodes. On the other hand, you've already been able to master Ten pretty quickly, so it's up to you to practice it regularly to smooth your aura."

"O-Osu!" You reply.

Later that day, after your training with Wing, you meet up with Killua expecting his usual hellish training. However, he made you do something different, one that reminded you of your very first day of learning.

"(Y/N), try to land a hit on me. If you do, I'll let you go to Heavens Arena," he speaks, taking a stance as he did so.

"H-Huh? It's only been a few days, how do you expect me to even touch you?" You question him. He didn't say anything in reply, only giving you a knowing look with his gleaming eyes and a matching smirk.

"Go."

_ _ _

"I... did it," you say unbelievably, staring at your fist as you did so.

"That wasn't so bad. I felt it a little too," he smiles at you, clutching his side lightly, though he wasn't in pain.

--A while ago--

As soon as he said go, you went straight for him. Though he dodged at the last minute, barely missing your grasp. You took this opportunity to try to land a kick on his open side as he dodges. However, he saw that coming and jumped over you, missing your kick entirely.

'Dammit, he saw through my feint.'

Your continue attempting to land a hit on him for the next few minutes. Finally, you were able to catch him off guard. You did multiple feints in quick succession to confuse him, which left him open on his side, you took that opportunity and punched him there.

--Now--

"Hey! You didn't hold back or anything did you?!" You question him, pointing an accusatory finger at him.

"Huh?!" He replied, a little flustered. "Do you seriously think I would hold back in your training?!"

"Hmm...." you say as you step closer to him, looking directly at his sparkling blue eyes for any sign of dishonesty. "Fine, I believe you,"

"Geez," He sighs deeply.

After that, You stood next to Killua as he talked to Wing about taking you to Heavens Arena. Wing had a thoughtful expression on his face. "Hmm... are you planning to take Alluka too?" He asks.

Killua shakes his head, "Alluka's not strong enough yet. It's possible that I might never let her go there even if she's developed a decent amount of strength."

"Geez... you're so protective," you giggle. Killua whips his head around towards you, "Of course I am, she's my sister and I swore to protect her! Wing and I should be enough to give her the strength she needs," he argues, wearing a comically irritated look.

"Well, whatever you say," you say teasingly.

"Anyways," Wing interrupts, clearing his throat. "(Y/N), I agree with Killua here about letting you go to Heavens Arena. It should immensely help you improve your strength."

"Really? Yay! I finally get to see what it's all about!" You squeal in delight. "Wait, what kind of place is Heavens Arena anyways?"

Wing chuckles, "It's the world's most popular battle site. A place where you can fight and earn money. It's an interesting system."

Your eyes widen in excitement. "A place to fight AND earn money?! That's a thing?!"

Wing nods.

"Woah... sounds cool..."

Killua turns his back on you, "Right? We're leaving early tomorrow, so be ready," he smiles slightly, looking at you through the corner of his eye. Shoving his hands in his pockets, he walks away to check on Alluka.

"Okay!" You smile excitedly, staring at Killua's back gratefully.

_ _ _

The next day, you stand in front of the entrance of the building with Killua, who was holding Alluka's hand. You look up trying to see where it ends.

"It's huge!"

"Yeah. This is Heavens Arena. 251 stories high, 991 meters tall," he explains, a happy, yet nostalgic smile gracing his features, as he looks up at the building as well.

You turn your head to look at him, noticing his smile. You smile brightly at him, "Well then, let's go inside!" You say, grabbing Killua's free hand and dragging him and Alluka inside.

"How are we supposed to fight?" You ask. Looking around.

"There are no rules for fighting, just defeat your opponent," he says. "The higher you go, the more prize money you earn. This is as good as it gets for those looking to make a living with their fists."

"And getting stronger!" You say, maintaining your bright smile. Killua chuckles at you.

'She's really excited to be here,' he thought.

"Oh, is that the line for registration?" You ask, spotting a very long line.

"Yeah, you go line up over there. Alluka and I will go ahead and wait for you at the venue. See ya!" He takes Alluka's hand, walking ahead. You nod.

After reaching the front of the line, a woman hands you a form. After filling it up, she takes it and tells you your number.

"(Y/N)-san. You are #1388. Please proceed ahead," she says cordially, gesturing to the arena ahead of you. "Thanks!" you wave, hurrying ahead.

Stepping into the arena, you see multiple people fighting in multiple rings. Referees stand in each ring to watch over them. Looking at the seats, you squint your eyes slightly, trying to look for Alluka and Killua. Finally, you spot a familiar mass of fluffy, silver-white hair. You smile excitedly, running over to them.

Killua spotted you first. He waves at you and makes space for you to sit. "That took a while,"

"Yeah, the line was really long," you sigh deeply. Turning to Alluka, you ask. "How's everything so far?"

However, she didn't seem to hear you, as she intently focused on the fights going on. Killua sighs deeply, looking at Alluka with gentle eyes. "She's been like this since we entered. All this stuff is new to her, so she must be pretty curious," he explains. "Yeah, I can tell," you chuckle.

Then, you hear the announcer speaking. "#1388 and #1087, please proceed to Ring F."

You stand up straight, feeling tense all over, "Well, it's my turn. Wish me luck!"

"Yeah. Oh, and (Y/N)?" Killua called.

"Yeah?"

"Just remember everything I've taught you, all right?" He says gently, giving you a reassuring smile. You stare at him for a moment, your heart unknowingly skipping a beat at his smile as you feel yourself relax a little.

"Yeah, I will," you answer, returning a smile to him.