1) Jungkook and Jimin are inseparable childhood friends, they have been always been together and attended the same schools, did everything together.
2) Jungkook is the younger brother/cousin of Jessica and Krystal Jung, he is very close to SNSD and f(x).
3) Jimin's dad is the older brother of Sandara and Thunder Park, Jimin is very close to 2NE1 and Big Bang.
4) Jungkook originally applied for SM and Jimin applied for YG but both were rejected and joined Big Hit.
5) BTS are very close to one another (As expected) but the fic focuses more on Jikook friendship.
6) Rest is pretty much same as RL.
It sounds complicated but I got the ideas from several other fics I read. I can help with the writing but my drawing skills :)