In the "Enemy Infiltration -Preface" book, we learn that the Dreadlords are infiltrating the different cosmic forces:
"In many ways, the titans will be the easiest to manipulate. Their singular goal is to impose structure upon everything they see.
Show them a force that opposes their drive for Order, and they will be consumed by their urge to eradicate it.
Their pantheon, so seemingly united in purpose, is vulnerable to fracturing.
The void lords all but welcome us with open arms. They are so preoccupied with their thousand truths that they ignore the lies we sow in their very midst.
I believe we can leverage their vast reach to position them as a foil against our other rivals.
We remain wary, though. Since they are observant of multiple outcomes, it is conceivable they could anticipate our coming.
Similar to the titans, the naaru and their keepers are singular in purpose. Their adherence to a linear path is an obvious shortcoming.
They savor nothing more than being proved right, so if they believe they have converted one of us to their precious Light, they will trust that agent implicitly.
The adherents to Life are the most insidious of opponents, perhaps because their nature is so antithetical to our own.
Still, we learned much from observing the link between their plane and Ardenweald, and we have high confidence that a vulnerability has been identified.
Our operative has already gained the trust of her target.
And as previously discussed, our position within the plane of Disorder is proceeding flawlessly. Consuming fel energy is not a pleasant process, but a necessary one.
The deception you have architected will bear fruit in the ages to come."
So, that means that the Dreadlords have a foothold in the Plane of Death (their origin), Disorder (demonic dreadlords), Light (Lothraxion) and Void (Dreadlords basking in the Void powers of the planet Sargeras destroyed).
Meanwhile, Titans are beings of Arcane and, therefore, have a foothold in that cosmic plane.
Yet, it is not the only force that they a foothold in.
Sargeras is a Fel-corrupted Titan. Although, he seems to be their adversary, so did Lothraxion seem to be against the Burning Legion and even orchestrated the death of some of his brothers. In the end, he deceived us all.
We've got Eonar, who has a foothold in the Life cosmic force as she (through Freya, whom she empowered) created the Emerald Dream and bestowed life powers upon Ysera and Alextrasza.
There's Argus, who has been referred to as a Death Titan by his datamined spell labels and "Drust-ish" spell effects.
The Seeker mount's description tells of how it was imbued with the Light by the Titans.
So, the only cosmic force they don't seem to have a foothold in is the Void.
This brings me to my next point. If the Arbiter was de-activated by the death of Argus (as the cinematic hints at, with the red-ish comet):
That means that Argus is, indeed, a Death Titan and that the Arbiter is, probably, his creation. They are, perhaps, linked together as if he empowered her to take on this role (similar to Eonar and Freya). Much like how Ra fell into depression once he learned about the Titans' demise. That would mean that the Eternal Ones are the equivalent of Azeroth's Titanic Watchers. And, before you lunge at me with "but, their power level was described as Titan-like!", hear me out. Some accounts claim that the Eternal ones arrived after the creation of the Shadowlands. Mirasmius, a sentient mushroom in Ardenweald, says the following:
"There was a time when hard work was valued in these parts. Of course, then she (Winter Queen) came along and got all fancy with her trees (Dream Trees) and groves. Nobody remembers old Marasmius."
Yet, he also says:
"I've been down here for ages. I remember the early days, it was just me and the Queen herself. We kept awful busy back then. She's a real hard worker too..."
So, it is unknown if she came later on, or alongside him.
It was, also, implied that there was a time "before the Maw was called the Maw." Moreover, The landmass within the Maw consists of pieces of land that have been ripped from a realm that was destroyed upon entering the Maw's atmosphere and whose pieces have become burned and desiccated. The Jailer pieced these together into a single landmass by throwing out chains in every direction within the Maw from Torghast and pulling them inwards.
These suggest that the Eternal Ones shaped the Shadowlands in their image and ordered it, accordingly. Much like how the Titans shape and order planets, using their Titanic creations. This is, perhaps, why the Shadowlands are ordered in the first place. Why souls are sent by the Arbiter to Bastion if they are drawn to service, to Maldraxxus if they were mighty in life, to Ardenweald if they were part of the natural cycle, to Revendreth if they sinned and to the Maw if they are irredeemable. The jailer wanting to tear apart this ordered system is like Sargeras' old lore - he saw order as a flawed thing and wanted to destroy it.
On the other hand, they could be the creation of the First Ones, who are said to have created the universe and its cosmic forces. The only question is, if Order is associated with the plane of the Titans, and not Death, why are the Shadowlands so ordered?
Archon: "The order of the Shadowlands depends on the execution of our eternal charge".
What do you think? are the Titans as devious as the Dreadlords, infiltrating the different cosmic forces? Do they have a significant foothold in the realm of Death?