Killua and you were teammates when you were 14 years old. You and him are both pro hunters. Both are grateful and appreciate each other. But later split up to go different paths

It is 10 years later

Killua accidentally meets you on a small street

He runs after you, patting you on the shoulder

"Yo! Long time no see, huh?"

He is grown much older, taller, stronger, more mature, and his voice is deeper