Things to know: some dialogue taken from episode 61 (2011) and volumes 17, 18, and 19 (Viz Media translation). Takes place from Greed Island on.

Inferiority Complex
An individual's belief that they are unworthy.

"I just wanted to show off this game to you."

Something about those words had gripped Gon tight and wasn't letting go. Try as he might to shake them off, they clung like a parasite in his mind the whole day; the world was being polluted around him as he listened to Nickes' group talk, reason slowly being taken over by emotions until he could barely stomach hearing to how Ging's game was being treated. How it was some cut-throat survival game where the most ruthless prevailed, where they had to cheat to win, where winning was the goal—

He couldn't stand it.

…

Gon still had enough of his mind left and guilt circulating to apologize to Killua afterwards. He tried to play it off, fully expecting some kind of retaliation (or at least some hint of displeasure), but instead Killua did what Killua does best.

Killua grounded him. Among the scattered feelings of disappointment (he's not here. Why isn't he here?), excitement (this is Ging's game! He wanted to show me his game!), anger (look what these people have done to Ging's game!), Killua had managed to ground him.

"Killua…"

"Hmm?"

"Thanks."

Killua's wide-eyed surprise spurred Gon on. The world seemed so bright, the sunlight accented by the colorful buildings and people, lighting up his friend too. Warmth was gathering in his chest in such an overwhelming rush, gratitude welling up in his throat, and he needed to express it, let the other boy know how important he was before he burst.

"I'm glad you came with me. No…"

(That's not right. It was more than that, but the words he was looking for were just out of reach.)

"I'm glad I got to know you!"

(a half-truth. The best he can manage.)

Killua turns away, the light no longer catching in his hair. "Cut it out, moron. You're embarrassing me.

"Why? I really mean it!"

Gon has never been so close to Killua before. Their noses are nearly touching, their breaths mingling with each sharp exhale. He can see the life sparking behind Killua's eyes, emotion that can't be seen so easily from far away, and its presence irks Gon more, makes him furious he can't comprehend almost anything swirling in their depths beyond mirrored rage.

"You need to be careful! That monster could have killed you! What would've happened if Biscuit wasn't here!?"

"She was!"

"But what if she wasn't?!"

"But she was!"

Biscuit's made herself scarce, having sensed the escalation from their usual bickering to actual fighting long before they did. Killua probably caught on quick too. Gon had no idea it was happening until he realized he was yelling (of course he was he last to know). The genuine anger had surprised him, overwhelmed him, and aiming it at Killua left a bad taste in his mouth even as they continued to fight, neither sure exactly how to stop.

"Are you stupid?!"

Gon doesn't show any signs of how deeply the words hurt coming from Killua, the boy who can do anything, figure out everything.

"Yeah, I'm stupid!"

"You—" Killua shakes his head sharply as if getting rid of a fly. "Do whatever you want! Go ahead and jump right back in!"

"I will!" And if Killua didn't turn his back, Gon would've. He would've jumped right in to prove his point, but with those eyes off him and Killua storming away, his hunched back the only sight for miles, Gon's rage cools quickly into a crushing, hollow inadequacy that immobilizes him, drags him down until even taking a step is impossible.

Gon watches Killua go until the inevitable flash of light that signals his departure.

He sits down and brings his keens to his chest. Behind him the pit is silent, not even wind whistling through the cracks in the walls. He wonders how long it will take for the monster to respawn or if it even will. He can't remember if they got the last card.

His arm throbs painfully. Now that anger and adrenaline are leaving him, the pain is sneaking into his awareness and demanding attention.

It had been a slip-up. Gon's plan had been working, despite what Killua thought. He'd just needed the monster to strike the wall one more time, and if it hadn't strayed from its usual strategy and managed to land a solid hit on Gon— he'd barely managed to get his arm up in time to avoid broken ribs— everything would be fine.

Are you stupid?!

No, he should've known not to get too comfortable with the attack pattern. This is Ging's game, and that man would never let someone win so easily. Maybe he should have told Killua or Biscuit what his plan was, but without even thinking he'd just run out of his hiding place and everything had been going so well until it wasn't anymore and then everything happened so fast—

…He screwed up, plain and simple.

Gon returns after an hour. Killua is nowhere to be found.

Biscuit wordlessly passes him dinner, waiting until his mouth is full to lay into him for his mistakes, but it lacks the usual intensity. Maybe she can tell how useless Gon still feels.

He finishes his meal and helps clean up, taking it upon himself to do the dishes. Biscuit wants to know what's wrong, asks him to explain, and Gon does his best to explain, but he's unable to put a name on the heavy weight in his gut he doesn't really want acknowledge.

Gon keeps looking into the distance, searching for the telltale sign of Killua's return, and the relief when he comes back is enormous. Gon continues like everything is normal, and things gradually become normal. After all, Killua has done his job. It was Gon who screwed up.

Once again, Killua was doing his job.

…Or was it being Gon's friend?

Rage.

It boiled hot and deep in Gon as he saw the realization dawn in Killua's eye, his own anger reflected in familiar eyes, and a ruthless plan formed almost immediately. Because this wasn't a dodge ball game. Not anymore. His friends almost died.

Killua almost died.

This was war.

He barely paid any attention to Biscuit as he went on the court, only one sentence really making it through: "Go on, beat him even if it kills you."

"I will!" Gon could do this much. He had to completely crush Razor.

Killua helped. He supported Gon without question, and that faith made him want to go all out with his Nen, irritating him when he couldn't get enough power to send Razor flying. Gon didn't think of the consequences until he noticed Killua flinch from the corner of his eye as he caught the ref's toss.

The ball hurt his hands.

He needed a Plan B—

"Okay, another go! Let's take Razor down!" Killua's determined eyes fixed on Gon's surprised face.

…Gon nodded, the good feeling in his chest barely breaking through his anger. This was their fight, and they'd do this together. Killua could handle this. Gon knew he could. It was only Killua that could support him like this.

"Okay!"

"That's enough!"

Gon barely manages to limp into a shady spot near Killua before falling asleep, exhaustion sweeping over him in one giant black wave. Whatever Cookie does to him while unconscious has him waking up to a brighter world energized and in one of the best moods of his life.

Killua looks down at him, amused when Gon attempts to get up and can't, muscles still too relaxed. Gon huffs and looks back, smiling when Killua begins to laugh.

Gon feels like Killua is closer than ever before. With the sun shining, framing the paler boy just right and the fluttery feeling Gon's been having coming back full force, words well up again, threatening to burst out into the air with exactly the words he wants to say this time.

But then Killua's bandaged hand awkwardly tries to brush his messy hair from his face, Gon's eyes following the motion. Killua's hands block out the sun with out thick the wrappings are, making Gon feel cold, and he gets up to resume training.

"What will you say to him first?"

"I'll introduce him to Killua, of course! And I'll tell him he's my best friend!"

Gon beamed at Biscuit, tightening his hold on the card Killua helped him get. The words weren't what he really wants to say, but he offered them as thank you to Killua, wondering if the other boy understands the weight behind them.

"Stop it!" Killua exclaimed, embarrassed like always. But why was he embarrassed? "Cut it out!"

Days blur together, but that's okay because they're going to rescue Kite.

Kite is alive!

They're going to help Kite.

He'd never be beaten by a guy like that!

Gon will get Kite fixed.

He's waiting for us to come back for him!

Kite is okay.

We've got to get stronger and go back as soon as we can to save Kite!

Right?

("Yeah. You're right," said Killua)

but somewhere along the line, Killua stops smiling. He's far away where Gon doesn't think he can reach, and it seems like he'll disappear at any moment and Gon can't do anything about it. Are things okay? He doesn't look good, but surely Killua would say something?

("Killua, did something happen?"

Killua says nothing. He's never said anything.)

Gon can't focus he needs to stay focused on Kite Kite Kite because he's hurt and needs help and Gon can do this. They're going to rescue Kite.

They're going to rescue Kite. Gon will get Kite fixed. Kite is okay. He's going to rescue Kite. He's going to rescue Kite. Gon will get Kite fixed. Kite is okay. He's going to rescue Kite. He's going to rescue Kite. Gon will get Kite fixed. Kite is okay. He's going to rescue Kite. He can't rescue Kite. Gon will not get Kite fixed. Kite is not okay. He can't rescue Kite. Gon will not get Kite fixed. Kite is not okay and it's Gon's fault it's all Gon's fault he's killed him it's all his fault always his fault why does Gon only cause problems it's all his fault he's useless he should just disappear he needs to make things right and disappear

Time passes.

The end is rushing towards them, but bitterness is far from the emotion he's feeling. There's none of that sickening, all-consuming rage. There's not even sadness. There's acceptance.

Gon stares at the little girl who saved his life, who is taking his best friend away, who he can't really hate. She'll take good care of Killua. She's not like him. Killua's affectionate with her, and open. He smiles. He tells her how important she is. Gon's never heard Killua even say the word "best friend." He assumed.

His mistake.

"Sorry," Killua says, "but you're number two."

Gon smiles. He already knew that. Killua had never felt the same way.

Why would he?