You were Gon's childhood best friend. Still are, just havent contacted each other. But you were in Greed Island, an game that Ging, Gon's dad, created for Gon to find him. When Gon said that he had to look for you to Killua and Biscuit, they let him go look for you. He did, you wearing the hoodie he gave you. You had Gyo without realizing it, so you had seen all peoples aura's, seeing if they have a good or bad aura. When you met Killua and Biscuit, they were surprised to see you.