Thank you for liking my answer!! ;v;
Umm im kinda struggling to answer this bc i dont want to sound like a 'only i understand him and everyone else is wrong' person or that im insulting other fans that have a differing view from me!
For me, i find sh's persona to be really interesting bc i don't find him easily summed up at all. Physically, he's a lil guy(sry sohi) really lean and super light on his feet (which is part of why i love seeing him dance!) and has like dainty wrists but then his face is very Boyish as in, youthful and cute. When i saw that memories(? Or gag) stage ending fairy i thought 'aw he looks like a cute younger brother type', and his fangs give him a trickster/Puck energy vibe like he's a bit mischievous-lookin. All those qualities might lead one to make assumptions like that he would be messy around the house etc
But then personality-wise, it's a bit different than maybe i had thought... he's a bit of a neat freak, kind of really wants to experience bossing someone around and taking care of them as a hyung (and as another youngest child, i understand that lol) which he does w atn despite them only having a FOUR MONTH differencejshdjsjsks. He's a lil strict with manners (aka telling atn to get his hands out of his pockets lol) and that makes me wonder how he'll be when he's a very senior sunbae in the industry har har.....and he also has this vibe of being comfortable in his own skin/masculinity and that makes him come across (to meee) as confident and at ease and his natural cuteness that everyone around him sees and loves ARRRRGGHHHH i love my sohee ☹️🩷 idk i think w kpop its very easy to box idols into archetypes/personas that dont align w reality, and writing fic can make that expand into flanderization of an idols persona in the fandom which isnt always fun for me idk sometimes its like that meme 'he would not fucking say that' but then i reflect like 'well yeah he wouldnt this is fanfiction' hfdjkssksk another nothingburger answer but yeah. Here ya go 🩷

auuughhhh this question is lowkey tough for me to answer buttttt like with my very first rz fic (her heart) i just randomly thought of the idea and a mutual was like 'you gotta put pen to paper' and i was like yknow what YEAH and ended up writing fic for the first time in like 15 years lol
generally i get inspired by media/art that isnt from fandom... i usually feel very inspired by films i watch (im like 'hmmm how can i make this 1930s screwball comedy about rz rpf?' bc im insane) or books i read or some songs. the titles of my two fics are from poems that inspired me/imo heighten the reading experience if it's read....ive made playlists for my favorite rz ships that help me get in ~the zone~ and also some ones for specific wips. now that you can add notes to playlists on spotify i wanna add lil footnotes to them but then im like 'am i being insane' yknow?

:o well i guess it in part depends on the fic/au. so far i take one aspect (or more) of their persona that i have noticed and is relevant to what im writing and then i emphasize that aspect, if that makes sense?? umm here's a breakdown of my impression based on their public personas^^:
taro- he's obv very very cute and sweet but being the eldest and de facto leader (and having a lot of real world experience like having worked pt and as a dancer, been a student) i think he also could be "strict". i think he's confident esp when it comes to his expertise (ie dancing) and while that can put some people off, i also think it's gained him respect frm others. also i love his dancing style, he makes even difficult moves/choreo look 1. natural 2. fun and effortless and thats something i want to translate to his personality in writing too
es- i think he has a lot of interiority, being generally calm and having a good poker face means he can keep a lot under the surface...which can lead to people projecting a lot of their assumptions onto him. i also think its fun to focus on his more absurd style of humor and his being a weeb/otaku (i say this as a former weeb/anime+manga otaku lol) can lead to funny moments
sc- he's lowkey an ~enigma~ to me haha i think i didnt notice a lot of the depth of his persona until recently (my bad) but i do recall es once writing abt his mood swings/intensity and that had me go "hmm....". he can be a goofy goober but having trained for so long+having seniority/experience as an ex nct member means he also has this maturity and ease...he rly shines in variety content (the zip daesung one had me ctfu) or the yt show he did :D
wb- well ok so obviously as the center/being so insanely good-looking there's a lot of projection onto him, but wrt to him i like to focus on his professional 'quirks' (ie perfectionism) and his neuroticisms (ie the compulsions he mentions like theyre just silly habits), though i rly like how he's become more comfortable being silly in content/variety stuff instead of maybe feeling awkward and at a loss
sh- hmm i feel like the way i see him and the way maybe the fandom sees him dont super align at times...but i usually want to think abt things like his being a neat freak or how he's sensitive (no piercings, doesn't like strong smells like cologne, picky eater) but being such a skilled vocalist i think he's quite confident in that regard (though if i sounded like him i would be singing like 1000x more often in content TT even if it was annoying but im an annoying person so idk) and his relationship w his gender/presentation as a 'small' dude i think could be interesting to explore more idk idk idk i could talk abt him forever
atn- i think i like to focus on w this guy is his subdued persona/sensitive nature and how he's so comfortable in his masculinity that he is also very comfortable w the more 'feminine' aspects of his personality/persona. but also he can be bratty/sassy and thats endearing TO ME.....

uhhh long long answer that probably didnt answer ur question adequately but hey! i tried ^^;;;;;;