I think I might have missed something, but who hired the private investigator Nick Stavrianos (by calling him in his dream) to find Laura Andrews in this novel?
Total Spoiler Warning:
It isn't stated in the book. The implication, however, is that the events that took place retroactively came into existence by the combined influence of all the smeared consciousnesses, human or otherwise.
"What do you mean?"
"The entire planet, the smeared human race--"
"But they weren't... they still aren't. Not the whole planet, even now--"
"No--but if they will be, or might be, don't you think they could choose their past? You know what one smeared human can do--dont you thinkan amalgam of twelve billion would be able to tunnel its way into existence, by whatever means that would take?"
"It found a way to happen, and you were part of it, that's all."
So my "liberation" from the loyalty mod, from Karen, is more of a joke than ever. I am who I am only because I served as a conduit for this apocalypse, a fault line through which the future smeared humanity could force itself into being.
Quarantine. p. 275
If you've read Egan's Distress as well, there is a similar notion:
Existence retroactively becomes real from the point of discovery of the Theory of Everything.