The infection is basically another lifeform joining with you. After you get infected you die and get reborn as a symbiosis.
Aglaecwif tells us she will destroy our "vessel" if we don't agree to breed her. The eye tells us "who can you trust if not yourself?" If we get too much corruption we monsterfy and the other part of the symbiosis takes control...
In some way the infection spreads and forms some sort of hivemind network, probably just very primitive but still, it makes sense to give feedback to the Apostles for finding promising locations for infection across the galaxy... During our evolutions both parts of the symbiosis interact more, so we just have better access during that time, resulting in being able to "travel" to the Apostles and talk with them. Since monsters don't have evolutions, it seems to me that's just a side effect... If it's not, the infection can only be seeking out species that have evolutions? That almost sounds likes it's designed...
The eye is just the other part of the symbiosis, he can break Jake's control because he's part of you... Or atleast he's always there, not just during evolutions... But the eye is the link to the Apostles, the eye is the part that gathers all your memories and information from your dna once the evolution starts, him saying "take our power" more or less is saying the result of the evolution is coming now... Perhaps his goal is to become a single entity instead of a symbiosis and that's why he's asking for your agreement? But there's not much else in these talks during our evolutions... our reasons, our goals, our agreement? He tells who to eat and gives some more advice... But it's all for reaching the optimal final result...
The fact that the eye calls Jake "the failed heir of Authority" is another thing... If Jake is still alive he can still evolve right?
So that would mean the part of Jakes symbiosis that could inherit the powers of "Order" is gone? He's still a superhuman...
But okay, lets see what new information WW brings us with our 4th evolution...
This gave me a lot of things to think about. Good stuff.
Some thoughts:
1)
I don't think that high corruption is the cause for monsterification, or at least not directly. It doesn't make sense to me because monsters infect humans for a reason, and that's to reach level 5 and perform whatever function they want them too. Ella says this and she seems very matter-of-fact about it.
If it's the cause for monsterification, then it essentially means that corruption is extremely counterproductive and an oxymoron, because for one it facilitates a better connection between superhuman and monsterparent, but on the other hand it substantially decreases the chances that the superhumans will succeed in reaching their potential and perform their purpose.
If that's the case, perhaps there is a fundamental flaw with monsters. They are by design self-defeating and they require superhumans with high sense of humanity not just to spread their influence, but actually avoid extinction. However I don't get such vibes from the game and I think that monster society is fairly secure, at least for the time being.
This is what I think happens:
At some point, I think it's Ella that says that exposure to monster material,
especially of a related monster, can trigger an evolution. However since most monsters are descendants of a select few (arbiters, apostles, and whatever is higher up in the hierarchy), by being exposed to huge amounts of monster material, eventually you will be exposed to enough material that is related to your monster relative.
Corruption facilitates better connections between all monsters, not just monster-relatives. It allows the superhuman to better understand the language and their ways.
We also know that when eating superhumans, it's possible to be connected to their monster-parents, or some form of their consciousness. Happened with Jake and Danica.
We also know that power is the catalyst of a successful evolution, decreasing the chances for monsterification. Power seems to affect control, body capability and the effect of abilities.
So I think that whenever the superhuman is exposed to monster material, he gets a connection. He also gets some corruption (through infection probably). High corruption + a lot of connections ends up being disorienting and even maddening. So it breaks the superhuman's focus, he can't control his power, so by extension he can't control his evolution, and monsterifies.
I think that high corruption is the best thing that can happen to the relationship between superhuman and monster-parent, it increases the chances to both evolve and understand the purpose of the infection, but it's dangerous because it invites other entities to unintentionally mess with your mind, leading to monsterification. /Edit: With high enough power, even under these conditions, the superhuman can become essentially immune to monsterification even under these conditions.
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2)
I agree with your view on infection being involved in a symbiotic relationship and having some sort of sentience, or at least being able to perform it's functionality autonomously, facilitating connections, providing the framework for the abilities to manifest and probably more.
However I don't think that there is a balance that must be kept and as long as any side of the symbiosis gets stronger, the whole gets stronger and gets closer to reaching level 5 and fullfilling it's purpose.
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3)
I can't really see the Eye as the other half of the symbiosis. It seems to have a very strong sense of self, it calls itself an Origin and speaks to the MC as the Ether speaks to Alice. I have a hard time picturing one as being the abstract consciousness of our infection, while the other is a full blown Apostle.
I do however think that MC and Eye exist in some sort of symbiosis but it happened before the MC got his superpowers, from whatever accident damaged his eyes. I think it's a very weak avatar of the Body+Memory Arbiter that can only survive through symbiosis, like a virus, and tries to influence the MC to succeed in facilitating it's return to a "full existence".