I'm a bit puzzled as to how multiple islands got infected at basically the same time.
The islands are all shown as being on fire at once -- presumably as part of the cleansing process? So they must all have been infected by the time the cleaning crews got there. But those crews were notified as soon as Ensi realized Helga had already spread the infection; so before Ensi, even if she did get taken over by the kade, could have infected all those other islands herself. And it took some time for Hilja to infect her own island -- she had to first infect herself from the small troll, then develop the infection to the point at which she was contagious -- can't remember how long that takes, but several days, I think? And as she arrived on her own island uninfected (although controlled by the kade) she can't have infected all the other islands en route.
Did the kade take over multiple travellers at once, each from different islands?
Did multiple trollified people from Ensi's island escape to the other islands before the cleansers got there, despite Code Zero procedures presumably designed to keep everyone in place and despite the fact that nobody other than Hilja had been showing any symptoms at all yet and there appears to be at least some delay between first symptoms and loss of control of the original personality, and manage to spread infection quickly enough that it was already past containment on those islands also?
Did Hilja infect not only herself, but a batch of other mammals, and somehow get those mammals over to multiple other islands without anyone noticing her doing that?
Do people routinely travel between the islands with sufficient frequency that infected-but-not-yet-symptomatic residents of Ensi's island had coughed on people from the other islands? And, if so, how did Omni and Tuuri escape infection?
