Re: Dimension 20, I nominated G13 & Usha on Ao3 (but not through the Google form). When the movie store employees enter the world, they're thrust into movie character bodies, and the movie store employees can even talk to/have relationships with the movie characters that they're inhabiting. There are canon interactions between the "real world" characters and the movie characters. The movie characters also have existing relationships - for example, Jack Manhattan (character who gets possessed) is married to Lucy Santangelo in the movie, and then Paula (movie store employee who possesses Jack) can also interact with Lucy. Jack and Lucy already have a relationship in the context of the movie, separate from the context of the season. Hopefully this explanation makes sense!