I like the way you think! Definitely, post about the Chart Of Alone In Some Place fanfiction tropes. :D I'm mulling over the Island -> Idyll track... I think there's a particular type of Desert Island Story in which the Island itself begins down at its end nearer the Cave, but actually moves along the track and becomes an Idyll, if you see what I mean. People are stranded there, and at first it's uncomfortable and upsetting, but over time they use the things they find and make to create their own idyll, and it's delightful and timeless and who would ever want to leave.

Like--Swiss Family Robinson, or The Black Stallion movie (I know I read the book as a kid, but I don't have a clear enough memory of the island portion to know if it goes as idyllic as the movie does). Or, of course, The Blue Lagoon, which as you might expect provides the storyline for some sexy fanfic AUs.