Dzeeck So, let me preface this by saying this is a shallow dive into several of the terms and mythologies related to the entry. Some of the content I just couldn't find, so maybe a good deal of it is original. However, some key things that aren't are listed here:
The Dru (The Oak Man): Obviously a play on the ancient Druids of Ireland, 4th century BCE
Lugh: A god that he changes the tales of a great deal. Interestingly enough, Lugh in real-life mythology was the actual trickster, and the "trickster" used here is a separation of these two mythological concepts.
Breogan: the very term for his leaders is the irish word for "king", Breogan.
Artabros: A group of celtic people believed to have lived in the spainish penisula. Interestingly enough, he changed them to be pirates, even though they lived in-land, rather than the shoreline.
Navia (Lir, Athanos, mentioned lower down): Celtic goddess of rivers. he changed it to the "Ocean", and changed the gender to male. Not that big a leap tbh.
This is just a very basic run-down of what I was able to find. After all, I don't really want to be stuck on this for any longer than I have to, there's just WAY too much history (props to the author, must be a historian of some kind to be sure).
Comparatively, ours had none of this. Speaking for myself, it was all spontaneous, but for shadow or slave, it probably was too. That's because, and I'm sure I can speak for everyone here, I (we) believed this would be pure fiction. But perhaps I (we) were mistaken in that assessment.
I said it was a research paper, which was inaccurate, and I will retract it. However, it doesn't change the fact that a good number of the mythological figures he uses are not entirely his own. Granted, this was probably the most interesting of the bunch, due to the intricate lore, but once again, he drew too much from other sources, which makes it slightly inappropriate for the purely fantastical and spontaneous ideas passing around here. Maybe that wasn't your aim when you started this thread, which is fine, however...
I rest my case, do as you will.
edit: interesting side note, the era of the celts, druids, and the entire theme of his story is all set prior to the medieval ages (750-12 BC, as opposed to 500-1500 A.D.) I'm not one to nitpick (actually I am, what the hell), but these eras seem a little... off when you look at it from a real-life perspective, so it even fails the first requirement, "Dark to Middle age period" (just for reference, the dark ages were from 476-1000 A.D.) It's like putting cavemen with knights, they just don't go together in terms of times.