katsuki and Izuku. The best of friends never left each other's sides but katsuki had alot of confidence and pride and called izuku a nickname "deku" while izuku called katsuki "kacchan"

They were adventuring in the woods walking down a trail till izuku said "kacchan don't you think we're going to far?.." the katsuki rolls his eyes "don't be a weakling deku."