Now I remember what this setting really reminded me of! Spoiler following concerning the End of Fire Emblem 10 / the Tellius Saga, but it's a good comparison.
Hydaelyn and Zodiark remind me of Yune and Ashera from Fire Emblem 10. The seem to be at odds with each other, (Ashera) Hydaelyn sealed (Yune) Zodiark to rule her own way/form the world her own way, and initially, combined they are one entity, (Ashunera) the Will of the Star.