I posted a thread about how Dragon is likely to posess the Uranus and how Enel ad the moon people are linked to the ancient weapons. See it here:It is. Or at least I haven't seen anyone else posting a theory like this. Enjoy the read.
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Now that you suggested that Pluton is Raftel it got me thinking.... Since nobody lives there now... It must mean that the said ancient civilization there must've been killed off... It reminds me of that Ancient Kingdom in which I theorize all of the "D."s came from. D standing for descendant.
To make things easier:
WHAT IF Raftel = Ancient Kingdom = Moon people whom are related to Skypiea!?
Good theory though. Welcome to the club.