"Yeeeep-he's always been a sucker for anyone with piercings-"
H: "SHUT UP!"
His cheeks were actually going a bit pink-
"Oooooooooooo~Keigo's got a crusshhhh-"
H: "You are such a little brat-"
Yeah so if you're wondering they very much have a sibling relationship and yes there IS a reason why they know each other.