Since I know that Prophecy is part of a much larger, sweeping epic, but it is neither a sequel or prequel to any of the other parts of either the Stardust Warriors or Seraphym Warriors. It is, however, clearly related through the megaverse setting in both series.
Jeremiah Holyfield is a Conscienta, one of 12 advisors to Laud chosen to aid the chief god in the war against the dragon-demons led by Narciss, the original fallen angel. Jeremiah's job is to protect the Prophecy, which spells out how a group of children called the Vigorios will lead the war against the evil dragon-demons. For some reason, the prophecy is kept on the world of the dragon-demons. I'd think it wiser to maybe putting in on Revrum Natura, the home of the Conscienta. However, I'll just let that go with the Laud works in mysterious ways.
This novella follows Jeremiah escaping from an attack by the dragon-demons which destroys the village where he's been acting as the spiritual leader. He escapes with only the Prophecy scroll and starts a journey across Solsyl (the planet of the dragon-demons, which they call Dracwald). Along the way, he gathers some companions to aid him in the journey. His essential purpose at this point is simply to keep the Prophecy away from Narciss. He's literally heading for the hills to find a place to hide until the Vigorios begin their prophecized war against evil.
I think it's a good idea to read Odessa (the YA series) or Zarena (the MG series) first, which provides much of the details on the pantheon of the megaverse, the Vigorios, Solsyl, Dracwald, the role of the Conscienta, and how the demons became the fallen ones.
Rebecca is not making this easy on the readers, but I'm getting the feeling that the complexity of the universe she's creating is worth learning. I like Jeremiah, although he doesn't seem to have much practical sense for an immortal, but he's stalwart and determined, kind, and his thoughts loving toward those around him. He's got a tough job, and seems to be up for it no matter how difficult it gets.