Originally Posted by
MrThinker
Archaeotania was a monster begotten by the Final Days in a different city, that the Akademia researchers captured to study and understand what the Final Days actually did. It is through this that Lahabrea came up with the theory that the monsters born of the Final Days came from the ancients deepest subconcious fears, and came up with the idea of Guardian Forces, monsters requiring sacrifice of the entirety of an ancients lifeforce, that were designed specifically to combat the threat of the Final Days.
It can be theorised that the process behind the GF's would later be expanded upon by Lahabrea in his design for Zodiark, and the GF's can be considered 'demi-primals' of a sort (not the summoner-type demis, but just half-baked primals, which maybe primal Enkidu can be shoved under).