so here are the roles

muffet-sans
sans-mettaton
mettaton-temmie
temmie-gaster
gaster-ruins dummy
ruins dummy-monster kid
monster kid-frisk
frisk-toriel
toriel-chara
chara-asgore
asgore-flowey/asriel
asriel-undyne
undyne-grillby
grillby-alphys
alphys-muffet
mad dummy-papyrus
papyrus-mad dummy
lesser dog-napstablook
napstablook-the entire canine unit

and i came up with some backstory for some reason so chara and frisk would be the adopted children of asgore and toriel and after toriel dies from a sickness asgore uses the already collected patience soul to cross the barrier to collect more souls to destroy the barrier but ended up dying chara decided to take action ruthlessly collecting human souls so no one would collect their's or frisk, frisk didnt agree with chara's actions so they left to the ruins and asriel decided to become chara's body guard
muffet is a friend of mad dummy's and dummy kid is the younger sibling of mad dummy and they are the cousins of napstablook and metta

and lesser dog resides most of their time in the ruins after napstablook took their spot on the royal guard

papyrus spends most of his time mad ever since sans left him for fame . . . yeah that is all i have for now it was a silly idea