You know with a couple of edits this could actually be a FFXV "sequel" just give it a read Ardyn being one of the first beings created by Etro that could easily tie into FFXV's ending, Etro or a fal'Cie or God recreating the world of Eos, I'd go with the fal'Cie one because it would make the most sense, to find Etro's gate.