So... I need to sleep so I'll toss these thoughts here, before I get crazy... Here's what I think its happening:
thinking about how rii is having just the same condition as another character just at the same time the other one starts to get reliable. Seems like the book miki was researching: Multiple persona's, when one persona is about to act rashly in order to protect the master persona another persona takes over. Also first the delusion is about the older sister, now the younger one. I kinda feel it's only one person with multiple personas...
I was just thinking about it... (Or better: not sleeping because of this...) -.