Hello! I didn't know whom to ask this but maybe you or one of the followers could help. I have never heard Sehun calling Kai by 'hyung' even tho Kai was born in January so according to Korean age system he should be considered the same age as 93 liner. (Just like D.O who is friend/chingu with 92 liner (chen baek chanyeol) and calls them by their names only not 'hyung'.
Well, they were still both born in 1994, he and Sehun are still only a few months apart. For instance, It would be weird if like, Jongin didn’t have to call someone born in like June 1993 “hyung” (someone 6-7 months older than him) but then Sehun had to call Jongin hyung when he’s only 2-3 months older lol. Now, Kyungsoo is a full year older than Jongin, which is why he is called “hyung,” but Baekhyun isn’t quite a year older than Kyungsoo, even though he was born in ‘92, making them “friends.” Hope that’s not… too confusing lol
Actually, I just remembered an old radio show where Kyungsoo and Junmyeon explain each member’s relationship. It’s when there were still 12 members, so…