Mnemolic magic is related to the "Star Orphans", gods and heroes and demons that live between creations, which can include those reality-bending burps known as Dragon Breaks. Think of them as the all-stars between kalpas, if that helps. (That probably doesn't help at all, really.)
The main things I've taken away from this are:
1) "gods and heroes and demons" - I don't know what context MK used these words in. Based on what Nirn's mortal races call them, I would have assumed "Aedra and mortals and Daedra". But if MK was using the words in their real-world sense, he's perhaps referring to... "demiurges and mortals and [malicious] spirits"? But it's the word "heroes" (mortals?) that has me most intrigued.
2) "that live between creations" - this I initially thought to mean leaping between kalpas; continued existence through and in spite of Alduin's devouring of the world and a given kalpa's end. But other thoughts and sources lead me to think MK might've been referring to their where and not their when; are they primarily outside of the kalpas (as Alduin and other beings know them)?
This is a concept in TES lore that appeals to me a lot. So I did a bit of digging...
http://www.imperial-library.info/content/two-moons-one-sun seems to imply the former:
Who are the star orphans? Outer Mundi, I think.
Another source, http://www.imperial-library.info/content/vehks-book-hours-concerning-dragon-break, seems to imply both interpretations:
"...Of special note is the Blue Star, which the Alesstics call ‘Mnemoli', that runs through this part of the Aurbis every untime. The psijiics hold it in much reverence, and many of their folk make pilgrimages to Veloth when it appears because a mountain there catches fire at its passing. This mountain is reputed to be one of the last refuges of the Dwemer before they departed from this world...
"...according to the texts, Mnemoli is a wayward child of ANU, one of a pantheon of forgotten deities known as the ‘Star Orphans'... a tribe of gods and goddesses that apparently felt abandoned when the Sun Withdrew from the World-Making. Like many of her siblings, Mnemoli is both confused and delighted with the Aurbis, and explores its five quarters as best she can without the help and regulation of worship, which are not needed (by which I mean, always there) during breakings of the sideways wheel...
The Blue Star Mnemoli is a Star Orphan referred to both as a "she" and an "it" which merely runs through (and otherwise "explores") the Aurbis during a Dragon Break, and needs no worship (always is worshiped?).
But am I correct in thinking Alduin devours the Aurbis, not merely Nirn's mortals, to end a kalpa? Is it possible the Star Orphans enter and leave the Aurbis, both in order to persist between kalpas and on their own whims and desires?
Searching also brought up a star-related thread in which I found http://img718.imageshack.us/img718/4708/cosmologyofnirns.jpg. Then there's http://www.gamesas.com/index.php?/topic/862112-aedra/page__hl__star+orphans, and http://www.gamesas.com/index.php?/topic/858254-meridia/page__hl__star+orphans__st__20.
So, the Star Orphans are akin to the sun, et al, except in that they were "left behind" during the creation of Nirn and now move freely in (and/or through) the Aurbis, essentially on the fringes of a kalpa. Armed with this (alleged) new knowledge, I then cheerfully re-read the first MK quote again...
Mnemolic magic is related to the "Star Orphans", gods and heroes and demons that live between creations, which can include those reality-bending burps known as Dragon Breaks. Think of them as the all-stars between kalpas, if that helps.
... And now I really want to know, besides the Blue Star who appears during a Dragon Break, who the other Star Orphans are, and especially of the nature of their existence. MK's choice of words leads me to believe a Star Orphan may be, but is not necessarily defined as being a literal star. What I'm getting at, in fact, is that they might be beings not unlike the Aedra and Daedra, and even the mortal peoples of Nirn. Is it possible that like the Aedra, Star Orphans have less-immortal descendants on Nirn?
Have I made any sense of this? Any corrections and explanations would be much appreciated.