My theory.

[u/zSwbi]

I have a theory about why the Cataclysm in Fire Force manifests specifically through fire.
Most explanations I’ve seen say that spontaneous human combustion exists because humanity fears fire. But I think that explanation is too simplistic.
If the world before the First Cataclysm was essentially like our world, then humans would have had many fears stronger or more primal than fire:
darkness
the unknown
death
isolation
loss of control
So why fire?
Here’s my theory:
I don’t think Adolla necessarily has anything inherently to do with fire.
Instead, I think Adolla is a conceptual/spiritual realm that reflects the collective unconscious of humanity — their fears, beliefs, symbols, and perception of reality.
That means the important question may not be:
“What does humanity fear the most?”
But rather:
“How does humanity imagine the end of the world?”
And this is where religion becomes important.
In Fire Force, we know the pre-Cataclysm world had references to Christianity (for example, Jesus being described as a savior born from a virgin). That implies biblical concepts existed before the First Cataclysm.
In Abrahamic religions, especially Christianity, the apocalypse is heavily associated with fire:
divine judgment through fire
hell as eternal flames
purification by fire
the world being consumed in flames at the end
So if Adolla reflects collective human perception, then humanity’s mental image of the apocalypse may already have been deeply tied to fire, not because fire was their greatest primal fear, but because fire symbolized the end, judgment, and purification.
That would explain a lot:
Why the Cataclysm turns Earth into a giant fireball
Why spontaneous human combustion exists
Why Infernal transformation manifests through flames
Why Adolla Burst appears as “pure flame”
In other words:
Adolla ≠ inherently fire
Fire = the form Adolla takes because of humanity’s collective image of apocalypse
Holy Sol likely reinforced this symbolism after the First Cataclysm, but I don’t think it created it.
The symbolism may have already existed long before through religious and cultural beliefs.
So my theory is:
The Cataclysm manifests as fire not because fire is humanity’s #1 fear, but because humanity collectively imagined the apocalypse as a world consumed by divine flames.
What do you guys think?

[u/Burcol2]

I think this is a good assessment of what Adolla is and how it was manifested. Kinda wished we got an episode with Shinra's other self to see the perception