I honestly didn't add much, most of this is just the same conclusions you would come to from reading https://plato.stanford.edu/entries/democritus/#1
and other stuff on atomism if you've also played deltarune. I only stumbled upon this connection because I was reading On The Ends of Good and Evil which is directly referenced via Lorem Ipsum in Undertale, and it mentioned Democritus, and the shit it said about him lined up alot with Deltarune's dark worlds, so I had to look more into him.