Killua and Gon have parted ways And killua Is not use to being by himself again. Without the love and kindness he got from Gon he started be become like his old self, cold, uncaring. He would pick fights with strangers and didn't care who got hurt in the process. He couldn't even trust people anymore, he was protective over his sister and only let her see his true self. Alluka didn't know how to help her brother feel better but she did know she couldn't leave him in the state he was now. Alluka runs into a person with a kind heart and a warm smile and instantly knew that they Could help her brother the same way Gon helped him.