Then there's the photo of Tom; some kind of magic let Polly see it in the mirror at Hunsdon House. Is that another consequence of the fact that she is the one who can save Tom? Or is some benign magic in Hunsdon House deliberately showing her that to help out? Surely it's significant that she takes the photo out of the house, even though Laurel or Mr. Leroy apparently steal it back later.

Same as the magic that let Polly get inside at all, and let her listen in on Tom and Mr. Leroy... I think you could write a good "flipped perspective" fanfic pitying Laurel, "queen" of a kingdom that sometimes actively works against her (I wonder could she escape either, if she tried?)