Okay, so we can assume the mice aren’t indicators of which choice is ‘best’, since they sometimes pick the wrong thing. They aren’t indicators of probability either, because otherwise they’d always cluster towards the choice she was going to make anyways; there wouldn’t be a way to pick a choice with less mice, since they’d jut move over to whatever was most likely at any given moment. So maybe they aren’t indications of what she should do, maybe they are indication of what she has done.
So, bear with me here, if the mice represent what she has done, than that means there are/have been a bunch of prior incarnations of her. But then how can the mice switch choices? Maybe the mice are concurrent ‘hers’ and they signal the choice the other incarnations are making… thus the others might change there minds, and the mice hope between the choices. Which brings up the fact that if she can see them, they can probably see her. Which means in a good handful of universes she’s a mouse.
But then where did newspaper mouse come from? Why does that mouse seem able to interact with her? She obviously can’t see the other universes where she is a mouse, so why can this mouse? Maybe that mouse is the Uber-her? Which would mean that version of her could see all the other versions, but has chosen to follow her, or the universes near her… hmmm. Or maybe it’s just another her near her in the tree that is focused on interacting with her instead of with it’s own reality…
So maybe she can only see the universes (or realities) ‘near’ her in terms of reality branching. Thus as she makes choices the other mice don’t, she moves from one group of neighbors to another. And since the newspaper mouse is active in her reality, that means it can only be seen in realities that are still identical. Which would be very few, since she’d need to have made choices in all of them that would put her in the same physical locations in order to interact with the mouse.
Which would also mean that the other mice would always be ‘in sight’ and that she’s spent her life walking around in a herd of mice. Which is an amusing thought. Some of them would be a little ahead of her and some a little behind, and they’d drift off –as the other her made slightly different choices– until they faded out all together.
Hmmm… *ponders ponderables*