First of all, wow - this is an absolutely wonderful analysis! I agree with pretty much every point being made here, and I appreciate the in-depth sourcing!
And second, because of the above, I think it would be remiss not to take that analysis to its conclusion by also accounting for three other texts that did not appear here - the Trial of Vivec, C0DA, and Sermon 37, in that order.
(as a disclaimer, I acknowledge that the texts listed are both controversial and delve into metanarrative aspects, but imo they are instrumental to seeing how Vivec's character evolved in MK's writing and what the endpoint of that development ended up being)
To start with, the Trial of Vivec plays with the theme that you have previously pointed out regarding the infantilization and almost objectification of Nerevar - specifically the idea of Vivec's dynamic with Nerevar, and more importantly its reversal, being a stage in their quest for an equal relationship.
Something MK has spoken about in the Trial and later commented on OOC is that the Tribunal's murder of Nerevar is an act that did indeed happen - not only that, it is a decision that they regret so deeply that, when they drank from the Heart and achieved apotheosis, the universe that had rewritten itself to accommodate for their apotheosis was such that his murder never actually happened.
On the murder of Nerevar by the Tribunal (2004-12-09)
Fan: I don't believe vivec did it, pure and simple. Alma might have, sotha might have, the guar with rabies might have, I don't care, but if vivec did it I think he would want you to cut his head off at the end or something.
MK: Nope, I'm pretty sure he doesn't want that at all. He's been pretty clear on what he wants.
Fan: It was a terrible, terrible thing. And none of them ever forgot it.
MK: Not even after it never happened.
In the current timeline, post-Red Moment, the Tribunal did not murder Nerevar. And yet, this timeline only exists because the mortal Tribunal did murder him. This duality lies at the crux of the Trial: the idea that Vehk the mortal and Vehk the god are essentially two different entities, and from that arising the question of whether the latter can be judged for the sins of the former, when he was born into a new timeline in which that sin was never committed, let alone by him.
As Vehk and Vehk I hereby answer, my right and my left, with black hands.
Vehk the mortal did murder the Hortator.
Vehk the God did not, and remains as written.
And yet these two are the same being. And yet not, save for one red moment. - Trial of Vivec
Yet at the same time, as Vivec says, while it was within his power to erase at least one account of the murder - his own, hidden within his secret writings - he explicitly chose not to do that so that the Nerevarine, and only the Nerevarine, would be able to learn of this and have the sole right to judge him for it:
Why did I leave the Nerevarine two accounts of his death, one that I could have easily erased from the minds of my own people? Because he is Hortator, GHARTOK PADHOME AE ALTADOON DUNMERI, my lord and king in this world and the last, and as Vehk and Vehk I murdered him, then raised him, then taught to him to know, and so would I have it when he came to me at last that he decide. I give you this as Vivec. - Trial of Vivec
An echo of this desire is even seen in the game itself, where Vivec reserves the right to be judged by the Nerevarine, but only if the Nerevarine first earns the right to judge Vivec's atrocities by succeeding where he has not and saving Morrowind from Dagoth Ur:
Why did I cause others to suffer? I respect that question, and you for it. The most I can say is: I did the best I could, as I saw things. Can you, mortal, presume to judge the actions and motives of a god? But, because I need you, and you need me, I will make an accounting for my sins, to you. But not now. Destroy Dagoth Ur, and then we will discuss my sins. Then, perhaps, you will have earned the right to judge me. - Vivec's dialogue, TES III
When viewed in that context, Vivec's mentorial and almost parental dynamic with Nerevar is colored very differently: it is not merely an instance of hierarchy where Nerevar is infantilized for the sake of positing him beneath Vivec, but an almost penance-like reversal of their dynamic from the original timeline seen in What My Beloved Taught Me, where it was Nerevar who served as mentor to Vivec and raised him from the gutter into a full-fledged individual.
In a way, Vivec is repaying the favor by now teaching the mortal Nerevar of this timeline how to become his equal - but the motive is still deeply unhealthy, as Vivec expects not merely to be judged but to be murdered in turn, and considers that to be a natural conclusion:
If there is to be an end I must be removed. The ruling king must know this, and I will test him. I will murder him time and again until he knows this.
[...]
The ruling king is to stand against me and then before me. He is to learn from my punishment. I will mark him to know. He is to come as male or female. I am the form he must acquire.
Because a ruling king that sees in another his equivalent rules nothing. - Sermon 13
The ruling king will remove me, his maker. This is the way of all children. - Sermon 15
Vivec understood. 'Say the words, Hortator.'
Nerevar said, 'Now I am the mightiest of your children.' - Sermon 34
You have already pointed out in the original post that Vivec has most likely suffered sexual trauma at the hands of his father, and the way this has skewed Vivec's perception of sexual relationships to be inherently violent and abusive. This, in turn, strongly colors Vivec's perception of himself and Nerevar as well: his understanding of their relationship is strongly reliant on the idea that one of them is submissive to the other, and Vehk the God has intentionally posited himself as Nerevar's superior.
This ties into much larger metaphysical motifs regarding the nature of the Aurbis that are probably way outside of the scope of this post, but suffice it to say that Vivec's (and really the entire Tribunal's) relationship with Nerevar is a direct echo of a foundational motif of the entire universe: the relationship between the Enantiomorph and their Lover.
A very very quick rundown - the Enantiomorph is a merged duality that consists of two chiral components which complement one another and exist in an unstable equilibrium reminiscent of a superposition, which is collapsed when it is observed by an outside Witness, who identifies the King and Rebel of the dynamic, collapsing the waveform into a singular outcome and becoming maimed in the process. This event is always predicated upon the Enantiomorph seeking the Lover, or the Catalyst, which is almost universally feminine but not strictly always, as we see with Nerevar.
A key point here: while the Enantiomorph is consistently portrayed as having agency and action/reaction, the Lover of the dynamic is almost universally seen as passive, almost trophy-like in that they are wanted and acted upon but do not possess agency of their own. The prototypical example of this is the Anuad, where the Enantiomorph of Anu and Padomay fight over the Lover, Nir, who is killed and her murder is witnessed by the children, the twelve worlds, who shatter in their alignment as part of the conflict.
This act of the Lover being denied agency is something that Vivec directly speaks on in Sermon 35:
This is the love of God and he would show you more: predatory but at the same time instrumental to the will of critical harvest, a scenario by which one becomes as he is, of male and female, the magic hermaphrodite. Mark the norms of violence and it barely registers, suspended as it is by treaties written between the original spirits. This should be seen as an opportunity, and in no way tedious, though some will give up for it is easier to kiss the lover than become one. The lower regions crawl with these souls, caves of shallow treasures, meeting in places to testify by way of extension, when love is only satisfied by a considerable (incalculable) effort. - Sermon 35
In this sense, Vivec's objectification of Nerevar takes on yet another layer - it is a representation of Vivec's own desire for Nerevar as his Lover, the one thing which he covets and thus acts upon with violence, murdering him again and again under the guise of "testing" until the dynamic is broken and Nerevar seeks out the center with his own right, becoming a ruling king himself and thereby gains the right to deal violence unto Vivec, instead.
C0DA comes into play in a roundabout way, and this is where the metatextual aspect comes in.
Prior to the text's release, MK has advertised/foreshadowed C0DA on his tumblr blog, with tags featuring some of the questions and mysteries that would be answered in it, and among them was "the true name of the nerevarine". This was seen as a bizarre thing considering each player's Nerevarine was meant to be canon unto themself - in fact, MK argued exactly the same after C0DA had been released, and the text itself never went out of its way to say "this is the Nerevarine's true name". So that raises the question, what is that name?
The answer is: Jubal Lun-Sul.
Something that MK has done before, in-character as Vivec, was referring to the audience/playerbase collectively as Nerevarine in the plural, namely in the original thread for Nu-Mantia Intercept:
Eight gods, eight provinces, eight as an infinity that stands upright.
Dig with him, my Hortators:
8. The Wheel, or the Eight Givers. 484
Some secrets stay hidden for ages. Viper-writing.
At the same time, MK himself has used C0DA as a text denying the notion of canon, positing the entire thing as his version of "the ending of Morrowind" - in other words, Jubal Lun-Sul is not just a random character, but it is MK's Nerevarine. More specifically, owing to the fact that the entire text takes place within the catastrophic dragon break known as Landfall, it is not merely a mortal Nerevarine, but rather the fully-realized god Nerevarine, one who stands equal not to Vehk the mortal but to Vehk the God, wielding all of Vivec's lessons about theory and terror and applying them against the Numidium, the ultimate Sharmat.
(as a small aside/self-plug, I have actually written a small analysis of the name "Jubal Lun-Sul" and what exactly that means for the plot of C0DA, which can be found here)
So why does all this matter? Well, that's because in this text we see two things happen: the marriage of Jubal and Vivec, and the murder of Hlaalu Hir. And it is the latter that is interesting to us currently, because Hir's entire character is essentially a representation of all the things of mortal Vivec that yet remain within the god Vivec, and must be removed - even when questioned on who or what Hlaalu Hir actually is, MK simply replied: a pronoun.
Jubal killed Vivec in C0DA? And on the nature of C0DA (2014-03-28)
Yes, in more ways than one, if one considers "Hir" to be a pronoun more than a certain best friend from House Hlaalu.
Suddenly, a lot of things become clearer about Hir: he is at once a best friend and a rival, someone supportive yet deathly jealous, the one who helps Jubal reach apotheosis and cut off his hands but at the same time the one who opposes him at the very end, requiring that he must be removed in order for them to truly get their "good ending".
And what ending is that? C0DA answers it:
VIVEC: I —
JUBAL-LUN-SUL: I —
VIVEC: WE.
JUBAL-LUN-SUL: YES.
But Sermon 37 clarifies further:
"The sign of royalty is not this," a signal blueshift (female) told him, "There is no right lesson learned alone."
[...]
The light bent, and Vivec awoke and grew fangs, unwilling to make of herself a folding thing. This was a new and lunar promise. And in her Biting she tunneled up and then downward, while her brother and sister smeared across heaven, thin ruptures of dissent, food for scarabs and the Worm. She took her people and made them safe, and sat with Azura drawing her own husband's likeness in the dirt.
"For I have removed my left hand and my right, he will say," she said, "for that is how I shall win against them. Love alone and you shall know only mistakes of salt." - Sermon 37
Although Sermon 37 was written after C0DA (and thank god for that, frankly, because we know that the original plans for C0DA were quite different and would not have played as well with that image), Sermon 37 leading into C0DA chronologically portrays a completion of Vivec's personal quest for Nerevar: from an urchin raised by him, to a god raising him in turn, Vivec's abuse at the hands of her father shaped her understanding of sexuality in a way that is representative of the very trauma that the Aurbis itself is founded on, the cycles of abuse passed down from divine parent to child to their children in turn, with the sole recapitulation to this being seen for the child to return the favor and replace the parent only to inflict the same abuse upon their children.
Vivec alone cannot break this cycle, and so inflicts it upon Nerevar as well. His love for Nerevar is, at the start, a reflection of his trauma - obsessive, predatory, admiration and jealousy becoming one as the only way to truly redeem himself in Nerevar's eyes is to be abused in turn, an entire worldview built upon dynamics of domination and submission. And that is why Nerevar is needed.
This scripture is directly ordered by the codes of Mephala, the origin of sex and murder, defeated only by those who take up those ideas without my intervention.
[...]
This should be seen as an opportunity, and in no way tedious, though some will give up for it is easier to kiss the lover than become one. The lower regions crawl with these souls, caves of shallow treasures, meeting in places to testify by way of extension, when love is only satisfied by a considerable (incalculable) effort. - Sermon 35
For Nerevar, Vivec is willing to become something other than "a folding thing", instead unfolding the grand design alongside Nerevar and taking the place of the Lover - opening herself to vulnerability in a way she formerly would not, but not just as a passive trophy to be acted upon but as an equal. In this way, Nerevar and Vivec can complete the endeavor without recapitulating the same mistakes, and Amaranth is achieved at last.
It will be addressed. There is one that will do it. WRONG - There is a we that will do it. Takes more than one.
