He was the moon. He caught the light Gon threw off and it made him glow.
He would never be as bright as Gon, he was meant to be in the shadows (Like a good assassin). But with Gon nearby he could be something other than a shadow overhead. He could be something to look up to, something to aspire to.
Gon's light allowed him to cast of the dark of his family name and approach the heavens.
Maybe, just maybe, he could become a star, shining just like Gon.