Interesting that both are adults though. Noticed that with a lot of the mentioned counter examples.

I love how this is such a stark reverse to the stated reason Peter Pans Lost Boys are all boys.

I don’t have one to hand but I’d see if you could find something through the Mythgaurd Institute. They tend to go in for this kind of thing. You could check out A Short History of Fantasy by Farah Mendelsohn and Edward James. It does touch on the history of portal fantasy as a subgenera but it doesn’t go very in depth as it’s not the main focus.

Worth noting that this is a pretty modern, don’t have exact dates on me but I believe it’s some time in the mid two thousands trend. Earlier Japanese portal fantasy tended to also be female led Inuyasha, The Vision of Escaflowne, and Magical Knight Rayearth are the big names I can recall. These also didn’t tend to be nearly as tightly trope driven, but that’s probably a separate industry issue.

I do feel that I have to point out that there are more Oz books where Dorthy moves to Oz permanently, brings the family and becomes the live in best friend of a princess, with political say so. It’s somewhat interesting that a lot of the ensemble story’s also send the protagonists home. Here I’m thinking of Digimon (my childhood), Narnia, magic tree house. As I’m typing this I’m also noticing that a lot of these aim younger than the various male power fantasy series as well.