What's the meaning behind the rings? (spoilage)

[NegativeS]

Look at these pictures.

Hydaelyn:

Zodiark:

The Endsinger:

What do these three arguably supreme beings have in common?

They have rings behind their heads.

Even in the murals--



--they have the rings behind their heads. (Though we never see Hydaelyn with the goofy mask)

What do the rings mean? Do you get a ring to hover behind your head when you apply to be a supreme being?

Are there any other bosses that have these rings?

If we ever get to see humanoid incarnations of the Twelve and they have rings behind their heads, I'm gonna lose it.