Who of the BTS members would be the most overprotective over Jungkook?
Probably Yoongi but in a subtle way.
In our fics, we have tried to show this trait where he doesn’t get too involved with his personal life, but shows some concern when he thinks he’s about to get himself in trouble.
This is first shown in his intuitive dislike of Jungkook’s first girlfriend Jia (shown in their breakup fic here). Perhaps fittingly, Jia also instantly dislikes Yoongi as I think she accurately perceives him as a threat to her and her relationship (as he sees right through her act). Likewise, when it is hinted by Jin that Jungkook is worried as she’s stopped taking her birth control, Yoongi reacts the most as he senses that no good can come of this development.
In a later fic, following Jungkook’s sexual encounter with IU, Yoongi is the only one to really notice that Jungkook is quite distressed at the rumour of her being pregnant, while the others just make fun of him. Jungkook also confides in him and tells him what happened between them and, instead of actively getting involved, he encourages Jungkook to talk to her himself to clear up any misconceptions.
Perhaps the most important way Yoongi has helped Jungkook in our fics is when he senses that the maknae is about to drunkenly cheat on his later girlfriend, Young-soon, at a party. He texts Jungkook to warn him to not do anything stupid, but unfortunately Jungkook does not check his phone until after. The following day and back at their shared house, Yoongi tries to check on Jungkook to see if he is okay, knowing what he has done, but Jungkook ignores him.
There are probably more examples, but these stand out to us. In real life, I think his love and protectiveness of Jungkook is shown in equally subtle ways, such as when he texted him that he loved him when they were going through a hard time, and also just by how much JK waxes lyrical about how smart Yoongi is, it shows the respect there is mutual.