basically, Yarn Dings Slarmon (or just Slarmon) is the Gaster replacement in my deltarune au Deltaspin, he is Normal NPC as Gaster. He was, being Normal NPC, the former Royal Chef leading the CCK (Canine Kitchen) (dogs from the royal guard). Also Alphys is Muffet and Papyrus is Asgore. I don't feel like typing anymore so here's a link to the source material.