Disclaimer: I have nothing to do with any of the HxH franchise :/

…

"Later!"

Gon walked purposefully toward his destination: World Tree. He knew that that tree possibly held his father, Ging. His goal the past two years or so was to find him and he was incredibly close. He could feel it. But even so, Gon felt an insistent tugging at his heart- a tugging that was pulling him back to Killua.

But Gon Freecss continued his pace, not looking back. For if he looked back, he was sure that he wouldn't be seeing his father anytime soon. If he looked back, he would go running to his best friend, his brother. He would forsake his goal for a new one- being by Killua's side forever. And he couldn't afford to do that to Killua. After all, the former assassin had spent the greater part of two years helping him find his dad. For Gon to give up the chance and run back to Killua would be an insult to his best friend. It would be saying that he had wasted this time. But still, Gon wanted to turn around more than anything.

It was a curious thing to Gon. He had never intended to make friends at the Hunter Exam. He was simply being his usual friendly self back then. Despite knowing that Ging had also taken the exam when he was twelve, Gon suspected that the majority of competitors would be much older, so he never expected to form any bonds. But in the end, he somehow managed to make three lifelong friends- one of whom he was even willing to give up the chance to meet his father for. Still, the boy didn't understand how he could say goodbye to Kurapika and Leorio so easily, yet saying goodbye to Killua nearly moved him to tears. Saying goodbye to Killua tempted him to abandon everything just to stay with him a little while longer. Just what was so different about this assassin-turned-hunter that tormented Gon's heart? He was his best friend- that's what was different.

They had been through everything imaginable together and still wanted to be by each other's side. They had their fun times- pillow fights, video games, adventuring and teasing each other. They had their training together and Greed Island and Heaven's Arena. But they also had times of heartbreak and struggles. Losing Kite. Seeing the devastation brought on by the Phantom Troupe and Chimera Ants. But still, even after all of that, they were struggling to leave each other. Because they were best friends. They didn't want to be separated, but needed to be for a short while. While Gon caught up with Ging and Killua protected his sister. Once the danger had passed, Gon was sure that Killua would call them and they would all meet up and he could finally introduce his best friend to his dad. And Gon and Killua would be together again. That thought was what kept the boy walking. He knew that they would always be friends no matter where they traveled.

Just as Gon arrived at the tree and prepared to climb, he felt something fall from his left jacket pocket. He frowned and picked up the folded paper that was now on the ground. Where did this come from? He unfolded it and tensed with eyes widening as he began to read the letter, hands trembling.

Dear Gon,

I'm sorry. I'm sorry that I could never say this to your face. That I had to write some cheesy letter and hide it until you'd eventually find it. I'm sorry for keeping all of this from you and I'm sorry for leaving. But I couldn't leave without telling you why. Why I've stayed with you so long. Why I'm leaving. And why you probably will never see me again.

Gon's eyes filled with tears that he struggled to hold in. What did he mean never see him again? What had he been hiding from him?

When I first met you, I had no purpose. Well, no purpose other than to kill. I truly believed that. No one had ever told me anything different or showed me that I was worth anything. Taking the Hunter Exam was more an act of rebellion than me trying to get out. I actually did plan on going home when I passed. I was just looking for a fun challenge and a bit of temporary freedom. But then I met you. I still believed that I was nothing more than a monster meant for murdering others. But there was the tiniest bit of false hope that maybe, just maybe, I could make a friend. And maybe I could be more than a monster.

Illumi interfered as always. He manipulated me. Made me realize, no, made me think that I had no other choice. That I had to kill and that I could never live a normal life with friends. I was so lost, Gon. I had been in that house all of my life, but never before had I felt so out of place. I didn't belong there- I knew that much. But I also believed that I didn't belong in the outside world, either. I was frozen in place, not knowing what I was supposed to do. But there you were. You came for me. You knew that my family was a family of killers. You knew that you'd be risking your life to come save me. You knew the dangers and yet you still helped me. I vowed that after that day, I would protect you with my life as you did for me. I would always stay by your side until there came a time where you didn't need me anymore. And so I did.

But it wasn't just out of debt that I stayed with you. It was because the impossible was happening. I was changing. I was smiling. I was laughing. I had a friend. No longer was a passionless puppet of darkness. How could I be when I was standing with someone who was so bright? I learned to use aspects of my training in ways that could help me be a better Hunter and to be a better friend to you. I trained with you and learned things that I would have never learned otherwise. I was always trying to become better, stronger, so I could protect you. You were the first one, besides Alluka, that I ever wanted so badly to keep safe. You're my most precious person, Gon. It's strange for me, because I can honestly say that I never loved my brothers. Maybe when I was very young, but that ended quickly. I don't think I loved my parents either- though I came closer to loving my grandfather and father than my mother. But I can honestly say that I love you, Gon. You're the brother that I always wanted. The family that I always wanted. That's why it's so hard for me to write this.

You are light. But you aren't without shadows. It took so long for me to see that. For me to understand it. You saved me from the darkness so I refused to see any darkness in you. You were light. That was all that mattered. You held no wrong other than a quick temper and some very stupid decision making skills. I was wrong. When Kite died was when I first saw the shadows. They came in so suddenly that I was afraid, but vowed to keep you from them. But instead of saving you from the shadows, I chose to ignore them and to try to distract you from them. I refused to see you drowning in the darkness. I refused to help because I was afraid that I would be trapped in their clutches as well.

But you went too far. When the shadows tried to take you and you gave up your fight, you told me something that I will never forget. One sentence that broke my heart. Broke me. "This has nothing to do with you." It may not sound like much. Out of everything that's happened, why is that the thing that shattered me? Because it did have to with me. It had everything to do with me. Do I mean that little to you for you to think that? Kite's death hurt me too, Gon. I wanted to rip Pitou into a million pieces. I wanted so desperately to shield you from the pain that I was feeling. But I couldn't. I didn't. "This has nothing to do with you." That was the first blow- to know that I wasn't wanted there. That you didn't want me. The second blow- the final blow, really- came when you threw everything away, not just me, to kill Pitou. When I left, you were still Gon. When I came back, you were a stranger. And in a flash, you were nothing but a mangled body on the ground. You told me once that you'd never seen me cry. Well, Gon, you made me cry like baby more than once that day. How is it that we switched places then? You became a killer while I was the one yearning for light and innocence. Struggling to pick up the broken pieces of both you and my heart.

I risked everything to bring you back, Gon. I went back home for you. I broke Alluka out for you. I put a target on my head for you. I faced Illumi for you. I made a bargain with Alluka for your life- one of the only requests that I can ever make to Alluka that will actually cause reproductions for me. I did everything I could to bring you back. To bring you back into the light.

But even after you've been healed. Even after gazing at the blinding light that is your smile- once again devoid of all shadows. Even after seeing your happiness return- I am still crumbling. I am still screaming inside and trying hopelessly to pick up those pieces of my heart that keep falling. And that's why I'm leaving. I'm running from you, Gon. Because I need to save what few pieces of me are left. I've forgiven you for what happened. But I will never forget. I will never forget your light or the changes that you brought about in me. I will never forget our games or adventures. I will never forget the darkness overtaking you. And I will never forget the blinding light returning. I will never forget you, Gon. So please don't ever forget me.

Your friend,

Killua

Gon collapsed to the ground, sobs shaking his body as his tears hit the paper. He wailed as he mourned the loss of his friendship. How stupid and naïve he'd been to think that everything was okay. He knew that he couldn't run after Killua now, for he would just be hurting the boy further. He knew that it was his fault that his friend was broken. And he knew that there was no way he could ever fix it. He also now knew that he never wanted to meet Ging. He never wanted to go home to Mito. He never wanted to see Kurapika or Leorio again. He felt all of them would be cheap substitutes for his dear friend. But in his heart, he knew that he would still do all of those things. Because Killua would want him to. And maybe, just maybe, the two of them might cross paths again. And maybe, just maybe, he could mend Killua's heart.