omg i love this question!! so so many good ones but here are some of my favs in terms of characterization (there's a lot of good fics out there featuring rik but these are the ones that come to mind first + anything by adultery while they're still up 😭)

https://archiveofourown.org/works/48713869 (suspended in a sunbeam - JELLYPOP): so so so yummy and such a good ggr study i love this fic to bits

https://archiveofourown.org/works/49463902 (gold of white (mine or not?) - rocketsummer): another rlly good rik pov ggr study that i love w/ very potent atmosphere

https://archiveofourown.org/works/51575116 (if you can’t hang - chaste): rik’s characterization in iych eats so bad and i love how gyubrik's relationship develops here

i have So Many Thonks anon there is just so FAWKIGN MUCH TO SAY abt their whole dynamic, their history, the implications of it all UGHWIRGHW!!!! like first of all when the yuehuaz went on idolpro they were.. children 😭 especially justin he was like YUJIN'S AGE and he'd alr been on a survival show which is so crazy to me. so when u grow up w ur friends like that you either stay lifelong friends or you never talk to each other again and well we know what they're like now. (ignoring dzr bc fuck him) but back then the bond they had was rlly lovely and im glad idolpro got to show that off bc it didn't focus on evil editing or creating drama thank god

for some context, idolpro was huge in china back then like entire variety shows were made just abt some of the popular contestants and some of them made careers out of simply being on idolpro. this is especially true abt next bc idolpro was the first place where yuehuaz were introduced as a group of 7. all of them were extremely popular and their whole group identity was heavily dependent on idolpro (next's chinese name is literally 乐华七子 aka 7 yuehuaz 😭 ). yh also debuted them almost right after the show, even before 9% disbanded, but that's a whole other Thing I Have Thoughts About. basically because idolpro had such a big influence on their group culture i think that's why quanzhe on asy was like That.

now on zzt and lqz specifically.... back in idolpro era everyone called zhengting a mom and it was all jokey jokes, but looking back he rlly was the Dad That Stepped Up 😭😭. he was a mom friend to all the yuehuaz but quanzhe especially was his baby, since out of the 3 maknaes (fcc lqz justin) quanzhe was the most innocent— fcc grew up in a famous family (aka unfortunately accustomed to a shit ton of hate) and justin alr was on pdx101 w zhengting. compared to those two quanzhe was rlly sensitive and too trusting. i don't think he fully understood how brutal c-ent is and u can rlly see zhengting baby him throughout the whole show. like i fully remember zzt's nickname for lqz being baobao 😭

going through everything that happened to next must have fucked them up too... scandals left and right, no promotions or songs, solo activities but only for some members, insane solo fans, fcc leaving yh completely... PHEW no wonder quanzhe turned out so jaded! you seriously haven't experienced bad management until you've stanned a chinese group. quanzhe just looks so tired on asy compared to how motivated and excited he was on idolpro and seeing that contrast is heartbreaking </3. zhengting must have thought so too like his expression from the moment quanzhe walked out in front of him was this depressing ass combination of pity, regret, guilt, and so many other things. man i felt bad for the two of them they were trying so hard to hold it together but yk zhengting's a sentimental crybaby (lovingly) so i knew he would start sobbing lmao. also quanzhe's age on asy is zhengting's age on idolpro hahaahahahhahahha

for next thoughts in general, i mean. all of them have tried so hard to separate their identities from the group 😭 at first when chengcheng went on shows he still introduced himself as a next member but now he barely even mentions being an idol anymore. wenjun's in a bunch of dramas, justin zhengting xinchun are doing random variety stuff, and quanzhe was completely mia before asy. i can barely even tell if they're friends at this point 😭😭 xinchun went on keep running w chengcheng recently ig??? and chengcheng follows justin back on ig????? im reaching now lmao but next is genuinely a concept at this point man did it ever exist or did i hallucinate everything?

tldr; if they were taylor swift songs, quanzhe would be nothing new and zhengting would be never grow up. anon pls slide into my dms so we can brainrot together <3