(opens my masterdoc) I’m glad you asked. mmm to be fair I’m open to diff interpretations of their dynamic and I tweak my own hcs a bit from time to time but my main dynamic of their overcomplicated aro polycule is usually like....

ruikasa - token /r relationship of the gang but I’m giving them minimum 2 years and 3 months to actually get together. rui is a loser pining for 2+ years and only realizes he has feelings for kasa like 1 year in cause he sucks at perceiving his own emotions while kasa is demiromantic and only catches feelings after a longer time. most frustrating slowburn the world has ever seen they’d probably divorce a few times before either of them even confesses but they'll kiss eventually do not worry.

mafukasa - unlabeled situationship-core sort of thing. I like to hc them as childhood friends (mfy took piano lessons from tenmama so she played w/kasa from time to time) but it takes them a while to remember cause they both have ass memory and forgor. after that tho they’d prob take some time to try to rebuild(??) their bond somehow but it wouldn’t be that easy since they’re both significantly different people compared to what they were like all those years ago so they need to kinda get to know each other all over again. also eventually they catch unspecified vague feelings for each other. not romantic not platonic not queerplatonic but a secret 4th thing. they kiss but it’s nothing srs they’re both very well aware that an actual committed relationship would probably make both of them worse (whether it's /lh or not it's up to you to decide)

mizukasa - not dating in any shape or form but they go on “dates” and are more affectionate w/each other than you’d expect when in reality neither party has romantic feelings for the other. my favourite romance baiters mzk would call kasa most embarrassing pet names as a joke and he wouldn't mind at all to everyone else’s surprise. I think they’d also bond over sewing + kasa would be mzk’s personal model mayhaps….

mizumafu - in a qpr mzk just kind of asked mfy if she wanna get married in the future for tax reasons one day and she agreed. and they actually do get married in the future trust. I hc mfy as transmasc so I loooove the idea of mzk helping mfy discover and come to terms w/her identity t4t mzmf is the only mzmf flavor on earth to me. doomed by the narrative but not in my heart lord let them both heal god bless.

mizurui - middle school exes (idgaf how much people complain ab this hc it’s hilarious to me if done right) but not in any tragic emo awkward way they dated “just because” but then they both kinda realized they’re arospec and that they never actually felt anything like that for each other. they joke about it every chance they get now. they also say they’re divorced now mizuki introduces rui to people like “So this is my ex husband😊” and rui plays along. they would def pretend to date to get couple discounts though + even after “breaking up” they made a deal to get married if they both get no bitches till they’re both like 30 they aren’t very serious people

mafurui - “boyfriends in law” except that rui catches some vague unexplained feelings for mfy at some point and has no fucking clue what that is. at first he’s scared that he happened to dislike the company of his own boyfriend’s other partner but after forcing himself to actually talk about it w/either kasa or mzk they just go “dude you sure you just don’t have feelings for mfy or something.” and it finally hits him. no way that loser confesses though he’s too emotionally constipated for that he just pathetically pins after mfy in a vague way + it doesn’t help that mfy may or may not also feel smth for him but unlike him she doesn’t make big deal out of it and instead randomly says things like “your face looks nice today” while rui is going through it

SORRY THIS IS SO LONG I actually don’t even think about them too often I just get hcs for them in visions every once in a while. hope all of this makes at least some sense😔