Where doth the Primals hail from?

[Seloria]

Summoned and fed on aether, the magical life force of everything and everyone, these mysterious creatures and their state of existence when not bound to Hydealyn...do they have a home plane, like the Espers of six? The lore seems to indicate they are tied to our realm and people, while the Twelve seem more the outsiders.

 

Then there's Atomos.

[Boo]

If I remember correctly the wiki says that the primals are in the aether that's well everywhere until they start hearing prayers, those prayers gather a large amount of aether at one point which create a primal. If I'm correct.

[Seloria]

No getting stranded in the Land of Summons as a certain young girl did? 

 

Not that it'd be a piece of cake to survive, given how hostile they seem to be this incarnation...

 

In all seriousness, what summoned Atomos?

[Rizenfell]

Here's Thancred's words on the subject:

 

 

Thancred:I daresay you've been curious as to how these crimes are linked to the primals. Permit me to explain.

Thancred: Having manifested in the physicalrealm, primals must consume aether if they are to maintain their presence here. And the stronger they become, the more aether they require.

Thancred: Now, aether exists throughout creation.It flows through all life, and permeates the very air that we breathe.

Thancred: Alas, this alone will not suffice tosustain the likes of Ifrit. Nay, he and his kind require a more concentrated source of aether─crystals.

Minfilia: It is for this reason that incidentsinvolving crystals can often be traced back to a primal.

Thancred: Which leaves us with the why of theabductions. To understand this, you must first understand how primals are born.

Thancred: When all is well with the world,primals possess no physical form. Their essence is dispersed across the great river of aether.

Minfilia: However, when the world is plungedinto chaos, those who worship the primals cry out to their gods for deliverance from suffering.

Minfilia: These cries serve as a beacon towardwhich a primal's essence is irresistibly drawn. It is this coming together─or “aetheric coalescence”─which grants the beings physical form.

Minfilia: Once born, a primal gains strengthfrom its followers' worship. The more numerous and fervent they are, the more powerful their god becomes.

Thancred: But the primals are seldom satisfiedwith such reverence as their adherents freely give, and in order to gain more power, they do not scruple to create followers. They do this by “tempering” mortals─a process to which you yourself were subjected.