As Oryx’s daughters grow older, they continue to increase their knowledge and dig deeper into their powers and abilities. At some point a few years or maybe centuries later after their birth, Oryx came across his daughters experimenting with death and a Hive wound that they cut between places. When questioned about what they were doing, Oryx’s daughters tell him that they are working on a way to separate an Ascendant Hive’s soul from its body. By storing its soul in its Throne World, they think that they can both make it harder for an Ascendant Hive to be killed and make their songs of death more powerful.

What they created was what we will eventually know as an Oversoul. They even call it that. How does this thing work? What's it's real purpose? Here’s my guess: Perhaps even Ascendant Hive have some vulnerabilities in the physical world. Maybe a powerful enough Guardian could kill one outright even in the real world? Or if not a Guardian, maybe something even more powerful like the Traveler could? But if their Oversoul is already stored in their throne world, maybe nothing can be powerful enough to kill an Ascendant Hive in the physical world?

Oryx is impressed by his daughters and instructs his son Crota to watch them in the hopes he might learn some cleverness from them. Then something interesting happens. Oryx leaves his daughters and travels somewhere far away to watch the Deep destroy an unnamed ancient fortress world. We’ve heard of the Deep acting on its own at least one other time, but this is the clearest indication we have that the Deep is able to move and attack and destroy all on its own. If there was any doubt before, it is clear now that the Deep (which we know better as the Darkness) is something more than just a another term for the Hive and their ongoing conquest.

After Oryx leaves, Crota follows his instructions to watch his twin sisters and begins experimenting with wounds to other spaces similar to what his sisters were doing. He cuts into a new space that neither he nor his sisters had observed or traveled to before, but instead of finding a new way to resist death or gain secret power, Oryx finds a strange race of intelligent machines. What he accidentally discovered was the Vex!

Vex come pouring into Oryx’s throne world and immediately begin trying to understand this new strange reality they’ve found their way in to. At first they can’t understand the physics and rules of the throne world. We’re told they try and construct problems, by which I think it means they’re trying to process and simulate the physics of this new reality with little success. But then, as Crota prepares to destroy them, the Vex start to figure things out. Specifically, they create a new Vex mind called “Quria, Blade Transform” that beings to understand the Hive’s Sword Logic. It somehow learns or deduces that killing things can grant it power. So the Vex begin to build units meant for war.

Corta moves to attack these new Vex soldiers, but the Vex teleport away from Crota and instead attack and defeat some 2,000 of Oryx’s Acolytes and 10,000 Thrall. By doing this they begin to gain power within Oryx’s throne world. So much so that even after Crota enlists the help of his sisters, they are unable to destroy the Vex. Oryx’s daughters even create annihilator totems and are able to destroy the Vex within Oryx’s throne world, but the Vex keep pouring through Crota’s wound and are even able to reinforce it so that Corta and his sisters are unable to close it.

Soon, a stalemate exists between the Vex and Crota, his sisters, and their Hive followers. Within Oryx’s throne world, the Hive are dominate. But each time they try and attack the Vex outside the throne world the Vex prove to be too powerful and are able to drive them back. Then, something very very dangerous happens.

The Vex steal some worm larvae from the Hive and quickly learn that by worshiping the worm gods they too can obtain powers similar to the Hive’s. The Vex being to alter reality with their worship and soon construct a priesthood dedicated to worshiping the worm gods. The worm gods Motive this and very quickly the worm god Eir demands Oryx return home and deal with the Vex himself. We’ll take a look at how Oryx reacts next time, but first I think we need to consider what just happened.

I think maybe the Vex started by worshiping the worm gods but that’s not what they ended up worshiping by the time our Guardians encounter them. We haven’t seen any worm gods in the Black Garden, but we have seen the Vex bowing and praying before a big blob of Darkness. I think what happened here is that the Vex, like Oryx, were smart enough to go over the heads of the worm gods and worship the Darkness itself. The Hive and even Oryx are all bound to the worm gods, but the Vex figured out that the worm gods were just middlemen standing in their way!

Ultimately, I think the worm gods were scared that they were going to lose their hold on the Hive. If the Vex proved it was possible to draw power from the Darkness without needing a worm growing inside them, how long would it be before Oryx or Savathûn or Xivu Arath realized it as well?

This is why Eri called to Oryx and demanded he put his house in order. They (the worm gods) saw that they were one step away from being pushed out as the power that controls the Hive. Oryx already partially stepped around them with his Tablets of Ruin and by speaking with the Deep directly. The worm gods have been telling the Hive that they must kill everything to prove their worth. Up until now, “everything” never included the worm gods. And they wanted to make sure it never does by having Oryx destroy the Vex before he or his sisters realize what is really going on.

There’s one other wrinkle in all of this. After Oryx comes back and drive the Vex out of his throne world, we are told that Savathûn was laughing because she tricked Crota into cutting his wound to the Vex’s space in the first place… But that would mean that Savathûn knew about the Vex before Crota or even Oryx did! So, not only did Crota not create the Vex, it seems almost certain that he wasn’t even the first Hive to encounter the Vex. I think what we’re seeing is Savathûn being one step ahead of everyone else like she has been in the past and like she will be in the future.

Sources:
XXXVIII: The Partition of Death
XXXIX: open your eye : go into it

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Next: 22: Crota’s Punishment and Oryx’s Plans