this is mainly a niigo concept i believe & i think vbs are more general, but i can certainly give you my thoughts…

MEIKO spawns first iirc, and witnesses akian at RW. i think she’s born of kensan’s idea of “wanting to provide a place of respite for the younger generation,” what with running the cafe & her wl card… motherly/looking after the kids yknow.

len (and by extension rin) is born from akty’s partnership as shown in wl, but i think he+rin are the more general concept of Aibou, and kind of slot into whatever metaphor they need to get across; eg representing akitouya’s fight in main story, an’s hazy feelings toward kohane in bout… len i would associate more with akty (touya+len kizuna “a partner to care for” & aktylen cc team name “like his older brothers,” len often trying to imitate akty by learning soccer and drinking coffee black) while rin is more representative of ankh (bout again, anrin kizuna “i love this street,” smth to be said about rin being the vs for both vot and lutf as well) also just. gender shenanigans.

luka is about freedom and honest emotions, so she tends to show up when a vbs chara needs to loosen up on their emotions, if that makes sense… bms is a very good example of this (as well as sdsc and wtwg so i can’t class her to one specifically) like. very carefree…

kaito is an interesting case because he’s got some curious akito parallels going on (guys who weren’t taken seriously even though they really wanted to be due to people’s preconceived notions of them, something akito falls into With kaito specifically) and he is in like. 3/5 akito events. so there’s that. he’s similar to luka in that he’s very carefree, but i think he’s more about offering alternate perspectives, or showing things in a new light with some fun quirky food metaphor. maybe a walking occam’s razor. he’s sillay

miku… i have a hard time nailing her down but she’s really the one to give the charas the solid push they need? the confidence to keep pushing forward in the face of hardship, and to get over that finish line… something like that (onto nothing.) i kinda yapped aimlessly but it makes sense in my head + the roles they play in events where theyre present

but of course the easy answer is:
in world link kohane is with luka and meiko, an is with miku, akito is with rin and len, touya is with kaito.
their fes cards are kohane with miku, an with rin and len, akito with rin and len, and touya with miku… which…huh .

if you made me choose i would say kohane miku meiko, an rin, akito len kaito (yaoi man), touya luka