Two cousins go to a convention dressed as Jacob and Evie Frye, The Twin Assassin's, and then transported to a completely different Equestria. One that is corrupted with gangs and violence, while Princess Celestia does nothing and exiles Luna.
I have ideas for stories with either crossovers with other shows or non-crossovers, so if you don't know what else to write about then pm or leave a comment and we'll discuss things