that sounds like a DustStory (Dust --> StorySwap) type thing and i dont think that AU exists yet, so yeah, though i could draw a Sans concept for it and maybe the story should be similar to DustSwap, since it has a similar connection?

Description: DustTale: Murderers Final Act DustTale: Creepy Smile Xal! DustTrust (basically a mixture of the newer ones and Legacy) (might actually swap this out with Devastating Judgement)