[I do not intend for these musings to be thematic, but in this case, there seems merit in following through. In all the resources available to me, I have only found two references to the origin of the Avatars. Here is one, followed by my notes]:

"Because the pact was broken that was made with Them by the Titan and thus he was himself betrayed, there came forth aspects of Them, full of the passion that was absent from Them in Their own Forms, and of their coming none now speak, for its destruction is writ in fire and blood in our skin and our blood and our bones..."

What is he talking about here? The Avatars? What is the significance of "Them/Their" versus "their"? Is there some connection here between the Avatars and the Materials? Is the destruction he is speaking of Zhe'ir-disna'ib? [Even now, I struggle in translating from the Elemental tongue, but I've been working on this one for a long time; it means something like (literally) the many-death time that led to the falling from the sun-place of the sun-people; I prefer direct, more literal translations from Elemental, as it captures better the fundamental nature of the tongue, but I have seen the same term, Zhe'ir-disna'ib, translated simply as the War of Heavenly Condescension.] If he is, he is right. I can find barely enough words on the beginning of that war to fill a thimble. Did the Avatar's start it? Nicodemus said something to me once that made me wonder if Mitsaru had once served stagnation. I don't remember what it was. The Avatars are aspects of the Materials. That seems to be the conclusion.