Okay, this idea came about because of a comment that living_endless made in a meme. Pretty much every supernatural canon ever has that one episode/issue where the bad guys make the heroes think that all the supernatural stuff is crap and they are really nuts.
It could be a lot of fun to figure out a way to do this on an island-wide scale. A group of people (or alumni) could be off island when the effect hits and it can be up to them to figure out what is going on and how to fix it while the rest of the people believe that this is the way it's always been or become convinced that they are really crazy.
In Charmed, the bad guy makes Piper believe that Halliwell Manor is really a mental institution where she is locked up because of her delusions about being a witch. He also convinces her that Prue, Phoebe and Paige aren't really her sisters but her fellow patients.
Re: Specific Ideas
It could be a lot of fun to figure out a way to do this on an island-wide scale. A group of people (or alumni) could be off island when the effect hits and it can be up to them to figure out what is going on and how to fix it while the rest of the people believe that this is the way it's always been or become convinced that they are really crazy.
In Charmed, the bad guy makes Piper believe that Halliwell Manor is really a mental institution where she is locked up because of her delusions about being a witch. He also convinces her that Prue, Phoebe and Paige aren't really her sisters but her fellow patients.