This is a fic that’s at least a few years old, but I can’t remember the title OR the author so I’m stuck. It’s complete and I think it was written for a minibang.
It was basically a twist on WIAWNSH where Dean touches a magical mirror (I thought it was called elderglass??? idk) that sends him to an alternate reality where life is just better, but without a djinn slowly killing you. In this reality, he and Sam ended up getting together whereas in the “real world” neither of them had made the choice to kiss each other after a specific event. Most of the fic involves Dean road tripping with other-Sam while trying to avoid telling him he’s really a construct inside of a mirror as he tries to get back to the “real world”.