Are the Twelve Primals too?

[Kaiser-Ace]

If only there were some larger source of efficient aether-convertible energy we could tap into... Gee, I really wish there was something like that standing around real obvious-like... But there's just nothing that convenient, is there? Shame.

<Cough> Cerulium <Cough> Ah man, these allergies I tell ya.

[Fenral]

<Cough> Cerulium <Cough> Ah man, these allergies I tell ya.

'Cause you see, I seem to recall an even more efficient, darn-near-limitless source that we just locked away for some silly reason or another... Gosh, but with so many lives on the line, I sure hope some better use will come to light...

[Kaiser-Ace]

'Cause you see, I seem to recall an even more efficient, darn-near-limitless source that we just locked away for some silly reason or another... Gosh, but with so many lives on the line, I sure hope some better use will come to light...

Um....Hmm.... A source we just locked away....hmmmm.....could it be that thing in..... but didn't that one guy...... Nah it couldn't possibly be. That's just loony.

[Alberel]

'Cause you see, I seem to recall an even more efficient, darn-near-limitless source that we just locked away for some silly reason or another... Gosh, but with so many lives on the line, I sure hope some better use will come to light...

I think I know what you're referring to, and given the way Rev Toll has gradually been constructed into a fortress-city over the course of the 2.x patches I'm willing to bet Mor Dhona will be seeing a large battle of some kind that will give us a chance to tap into that source.

As for the OP's questions on the Twelve. They can be summoned as primals, yes, but whether they really existed (or still exist) as non-primal entities is another matter entirely. My personal opinion at this point is that the Twelve aren't gods but rather vastly exaggerated legends based on real (though potentially immortal) people. There have been a lot of little hints in that direction throughout the game so far, one of the most notable being at the end of the FSH quests regarding how legends tend to get out of hand.

There's something important in the Heavens above Eorzea though. The Moogles claim to originate from there, where they lived with the Twelve, and several other quests have been pointing in that direction (such as the Ixali obsession with returning to the floating continent of Ayatlan). If you look over the Heavensward concept art as well there are several distinct architectural styles; we know which ones are the new beast tribes and the Dravanians, we know which are the Sharlayan ruins, we know which are the Allagan ruins, and some appear to be Ishgardian in origin. There is one distinctly 'heavenly' architectural style that we do not know yet though and in the last live letter the devs commented that these ruins in the sky would be part of the story. I think we may start to discover something of the truth of the Twelve in this expansion.

[ShionRasenka]

This is a very difficult topic to answer. Some of the Primals have had very different summoning methods from the 'traditional' way. Shiva and Good King Moogle Mog are the two that come to mind. It's hard to say if the Twelve are any different from primals, or if they are true deities who can just appear whenever they want. The only we'll know for sure is if SE decides to have one of the Twelve show up to help us out for some reason, or we have to summon them like a primal for help. If they're not truly deities, and they're no different than primals, then it's a VERY bad idea to try and summon them. If we did try to summon them like primals, I doubt they'd be the benevolent beings they're portrayed as. So until SE gives us more details on what the Twelve might be, we're pretty much in the dark.

[Rannie]

What if the twelve were really hydalen she does say she's all made one so the twelve could be different aspects of her. I remember after the blessing gets sealed minfilia says that the treaty with Midgardsormr was with one of the twelve however he said the covenant was with hydalen (I need to learn how to spell her name).

[treuhavik]

What if the twelve were really hydalen she does say she's all made one so the twelve could be different aspects of her. I remember after the blessing gets sealed minfilia says that the treaty with Midgardsormr was with one of the twelve however he said the covenant was with hydalen (I need to learn how to spell her name).

This is actually one of many theories we played with some time ago. But without further information, everything built to answer this question was a house of cards waiting for the slightest gust of wind.

[Rannie]

Eh I guess my beliefs (real life ones religious ones. Don't worry I won't go into it. ) tend to make the house of cards a bit stronger but as long as its not thrown off the burner completely...

[treuhavik]

as long as its not thrown off the burner completely...

Let' hope not!

[axemtitanium]

There are a couple different intertwining, interfering questions here. Allow me to try to disentangle.

1. There is no evidence that any "primal" must be based on a real thing that once existed. For example, King Mog is explicitly stated to be a moogle myth (which may or may not be true). On the other hand, Shiva is explicitly stated to be a real person, but it's clearly not necessary for this to be the case for something to be summoned as a primal. The other beastmen primals have ambiguous myth-like origins (yadda yadda Garuda, god of snakes yadda yadda)
2. There is no conclusive evidence that any particular instance or incarnation of a primal represents a distinct "entity". That is, when Ifrit is slain and summoned again, did the same "ball of aether" from the aetherial plane get retrieved? Is there a quantity of aether within the aetherial plane that is specifically marked "FOR IFRIT USE ONLY"? Does this aether have personal memories? Some primals exhibit behavior that implies that they have memories but that could possibly be attributed to memories imbued by the summoner(s).
3. Regardless of the above points, did there exist historical humans or literal gods named Rhalgr, Halone, etc. once upon a time in the distant past? If they were humans, it's possible that the legends attributed to them are tales that evolved and were passed down via oral tradition. If they were literal gods with superhuman powers, then the Twelve represent a new type of existence that has not been shown before in this fictional world. It's also possible that they never existed at all and their stories were spun from whole cloth by ancient peoples.
4. Regardless of the above point, if the enlightened races today prayed to their mental conception of the Twelve along with a large quantity of crystals, the result would literally be a primal incarnation of the Twelve (as the Ascians tried to encouraged the Ala Mhigans to do with Rhalgr). Whether this primal incarnation is connected to a distinct aetherial entity in the aetherstream or a historical personage is an open question (see points #1 and #2). But the result would definitely be a primal, if the summoning was successful.
5. Lastly as an aside, the "Twelve" summoned at the Battle of Carteneau were not actually primal versions of the Twelve. Louisoix specifically attempted to draw upon "a fraction of the Twelve's power" (whether or not they actually exist) to stop Dalamud. So those weren't primals either. It's unclear what the vision of crystalline spears that Louisoix saw before he turned into Phoenix actually was. The Phoenix that Louisoix turned into was definitely a primal, but it doesn't actually matter if the concept of "Phoenix" existed before for Phoenix to be summoned.

So to sum up, the "real Twelve" were not primals (if they exist), just as the "real Shiva" was not a primal. A primal is just something that has been summoned by thoughts and prayer. If someone were to "summon the Twelve", it would be a primal.