I think Azura was simply throwing a temper tantrum and not letting her usual followers into her Realm for a while. She was simply temporarily bound to Mundus and then had her physical body destroyed. She probably just had to reform in the waters of Oblivion and find her way back to her Realm like any other banished Daedra. But this is not usually something a Daedric Prince has to put up with because it takes a complicated ritual of name-calling and powerful weapons forged of godsblood. Most normal mortals cannot banish a Daedric Prince. Vivec knew how, and the hero of Battlespire knew the secret. The fight against Hircine's aspect doesn't count because he wasn't fully manifested. Obviously Akatosh didn't need any artifacts or magic words to banish Dagon, being a god himself.

The Hero of Battlespire had a piece of Dagon in the form of a sword anyway. It was as though he was wielding the Death Star.

I believe my exact words were "Oh. Well, good show, sport. You've trumped me. Before you banish me, would care for a sporting bout of badminton?"

They never want to play badminton.

While on the subject, it didn't take me very long to recover from my banishment. I had been roughly planning the Oblivion Crisis since I was banished, but I started investing most of my time in it about 15 years prior.

Well, you were in an plane outside of Mundus, so that may have help ya.

So Vivec achieved CHIM? That's what happened to him?

Some say Vivec did, some say Vivec did't, depends if you want to believe the obscure texts and the sermons.

I'd like to. So, his disappearance is him simply choosing not to manifest himself in a physical form?

Pretty much, if you want to believe he successfully achieved CHIM. Plus, it can be very boring being an all knowing, all doing being, especially when you are everyone but you at the same time. It's more fun sometimes to watch things as they play out.

Then can a being that achieved CHIM be called a God? A God that is not Aedra nor Daedra, but simply a God of their own definition?

A God implies some degree of symbolic power. While a CHIMmed individual may make himself a God, to have CHIM implies very little symbolic power at your disposal.

It depends on how you want to define gods. Whoever achieves CHIM is on a whole other level from the spirits called Aedra and Daedra. Imagine those as just characters in a dream, and the Godhead is the dreamer. People like Vivec who figure out how to merge with the Godhead are the Dreamer.

I like the idea that mortals are the many fragments of the Godhead interacting with its many fragmented concepts, known as the gods.

In short, Vivec still exists. He is not a God, for he has not chosen to exist as one, but he exists as an immortal being with no physical form, right?

A quick question about CHIM: If the et'Ada are merely fragments of Godhead also, then would a being that achieves CHIM have a greater capability than any of them, along with even Anu and Padomay?

At first there was the Godhead. Then, in a schizophrenic moment, it divided into IS and IS-NOT, Anu and Padomay. From them, they birthed their souls Anuel and Sithis. And when they two polar opposites bumped into each other, their interplay formed the grey. Within the grey, concepts, spirits, and beings came and went; the et'Ada. From the et'Ada, Mundus was created, using the pieces of what is now the aedra and Shor, with Magnus as the architect. Magnus and his fellow magna-ge fled to the Aetherius, avoiding to be part of Mundus and not wanting to stay in the waters of Oblivion. The daedra laughed at Shor's work, claiming that cutting pieces of themselves to create Mundus was a [NUMMIT] stupid idea, when they could make worlds of themselves, thus holding complete dominion. As for the mortals, some say they were lesser spirits. Others say they were gods who in order to survive on Mundus had to create progeny, with each new generation growing weaker and weaker.

When one achieves CHIM, they realize they are everything and everything is them, but they selfishly maintain their identity. Should one forget that they are an individual, they cease to exist and ZERO-SUM. Also, it's one thing to know, it's another to make the realization.

I get that (or most of it), but what happens when one achieves CHIM? What changes?

I've said this so many times already! When one achieves CHIM they become everything, everything becomes them, but still is able to hold onto their individuality. You're literally the whole universe, down to the smallest speck of magicka and whatnot. However, because of that, one runs the risk of no longer being an individual and ceases to exist.

With CHIM you must be able to say "They are me, I am them, I am me," especially the last part, or else you cease to exist.

Sorry. I just meant if there's any further explanation, but information is limited on CHIM, after all.

You open the Construction Kit and start puttering around inside.

Then why didn't you say so? Well, the only info you are going to get with CHIM is from:
The Commentaries
Sermons
Trial of Vivec
MK's posts

Or what Mehrunes Dagon said. Consult the manual if you're having trouble with the CS.

Answering the title question...

Under the belief that Vivec betrayed his/her past incarnation. I always assumed the Nerevarine got revenge on Vivec. Trapping Vivec within Azura's Star and binding his soul to a trinket or weapon "prison" for all eternity.

The Nerevarine is the player, and for that reason he is left out of accounted events after Morrowind to allow further player freedom. What the Nerevarine thought of Vivec could have been anything. I like to think the Nerevarine was offered the choice for vengeance, but turned it down, and yet remained somewhat disdainful toward Vivec. Of course, that is only my Nerevarine's actions.

Nixta, Vivec is safe and sound, at least that's what I gather from the postcards.

He will trouble the Mundus no more...he's having too much fun in planes unrecorded, thieving from them as is his wont.

And by "no more" I really mean "until the new Threat! To! Empire! Aurbis!" is put down.

Thanks MK, I'll sleep much better tonight.

I had suddenly awful premonition: Star Wars: The Vivec Unleashed.

By The Nine!
I just got a horrible Muatra-movie in my head... thanks for forever ruining Star Wars for me.

On another note: That's hilarious.