Responses

It’s a Korean book (manhwa). You refer to an elder male who you are close to as brother/uncle. In this case, he is saying “luke hyung” which is brother Luke but it isn’t limited to familial relationships. Luke-ssi asked to be referred to like that. A lot of manhwa use it. It’s like saying senpai in manga.
Stop with the BrOtHeR LuKe mah gawd