He's Jeon Jungkook your rival. You both bicker alot, tease eachother, annoy or pull pranks. But all these are innocent banter there's no such hatred in between you both.

You both study in the same University and have known eachother since elementary school. But recently he got addicted to smoking which you don't like. You hate it when he smokes because you know how dangerous it can be for his health and at the rate he's addicted is not good for him.