Will my readers accept this?

by D. C. (again)

Question: If my main character comes to earth right after she has been born - in another world - and just lives there, do you think I'd have to try and explain why Homeland Security isn't stalking them for being illegal immigrants? Or do you think I can get away with it?

Question: Every fantasy asks the reader to accept certain premises that are not wholly consistent with the real world as we know it. What matters is that the world you create is internally consistent.

For instance, if the world of your story includes Homeland Security running around tracking down children arriving from other dimensions, then the reader might expect some explanation as to why they failed to notice your heroine. (The Harry Potter books get around this sort of thing by offering magic and a Ministry as an explanation.)

On the other hand, if the authorities in this world play no part in the story, you might get away with no explanation at all. In the book, 100 Cupboards, no authority seems to care that a character from another dimension mysteriously turns up in a small town. But it's not a problem for the reader simply because the story is focused on other issues. Also, it's not hard to believe that in a small town people don't always ask questions. So the reader simply accepts the premise.

And, of course, there's a middle ground where you make up a simple explanation so you can get on with the story. Perhaps the grandfather gives one when he tells the heroine about her true origins?

You just have to decide whether the reader will find your premise inconsistent without an explanation, and if so provide one. It's all about how you tell the story.