As in this au frisk falls trying to find a flower(their special intrist) Mari catches them and end sup dying when they fall and comes back due to the flowers giving them limited time.

Cedar helps them only because frisk is a kid ans reminds him of pap. He convinced pap to help and snowdin becomes their sanctuary.

Eventually Mari dose notice she will die soon, convices cedar to take her to the barrier and so she can free monsters and frisk. Frisk finds out and like isha(heavy arcane insp)

Dosent want that and tries to stop them ending in a angst shot of cedar holding frisk in his arms as she screams mommy.