This Community refers to Undertale fan-game https://gamejolt.com/games/Disbelief_back_story/610945

and to fan-animation Disbelief! Papyrus

https://www.youtube.com/watch?v=VC-yGc8WQfc&t=3s&ab_channel=%E3%80%8CFeyt%2FEpicZX-Chan%3A3%E3%80%8D%E3%80%8CFeyt%2FEpicZX-Chan%3A3%E3%80%8D

Undertale by Toby Fox

Disbelief Papyrus by flamesatgames

Disbelief back story by Sahek seven (me)