Do you think the Prophecy of Deltarune existed in the Undertale world?

(Yes, I suspect people have talked about this before. Still, I want to.)

The Delta Rune that appears in Undertale is the same symbol that appears in Deltarune, but it is treated differently. The three triangles are said to represent monsters as a whole (rather than just the Three Heroes, which is the meaning implied in Deltarune), the winged circle represents the Angel, and the entire thing is said to prophesize the end of the monsters' imprisonment underground.

However, even in the context of Undertale alone, it's said that the Delta Rune is an ancient symbol whose meaning has been lost, and so implied that the modern interpretation was created after imprisonment.

It's very possible that both the UT and DR worlds originally had the same Prophecy of Deltarune: the Three Heroes and the Angel. However, in the UT world, the story was distorted and forgotten long ago. Perhaps in DR it was Gerson's historical work that rediscovered the original prophecy, while in UT, with Gerson locked underground, there was no one there to figure it out.

This is interesting mainly because of what the prophecy in Undertale could mean in Deltarune. The prophecy in Undertale, even changed over time, likely maintained a core premise: that the Angel would descend from above and bring freedom. And if the end of the prophecy in Deltarune - something we've only seen vague hints about - shares those same elements, then it could give us hints on where the plot will go.