I wanna talk about my DR theory about Ralsei's lightworld counterpart being the Deltarune's equivalent of the bible, or as I prefer to call it, Ralsei Bible theory.
There are a few things that make me think it's probable:
1- Ralsei knows a lot. He knows more than he lets on about the prophecy and the dark worlds and doesn't info dump all of it for plot reasons, but him having full of knowledge makes me think that he knows those stuff because they're all written in the Deltarune Bible.
2- Ralsei doesn't believe he can change the prophecy. He wants to, but he ultimately lacks the belief that he is capable of doing it. If it is already written inside of him in the first place, then it is impossible for him to change what is to come.
3- He can travel between the dark worlds freely. A Bible is an item that can be found in a school, a library, a house and especially a church, which are all the locations a dark fountain has been opened so far. If each place has a bible that would enable Ralsei to exist in all of them freely without turning into stone. He fits in everywhere.
4- The heal prayer. The healing spell being called a prayer makes it something that is almost definitely contained in whatever Deltarune's equivalent of the Bible is called. If Ralsei's lightworld counterpart is the Deltarune Bible that would easily explain how he knows the healing spell and able to cast it easily.
That's all I got right now, but all these hints make me like 70% sure that Ralsei is going to turn out to be the Deltarune Bible.
