5. What the fandom writes
The largest category is the high school AU: Shelby and Toni meet without the island, sometimes as classmates in Texas or Minnesota, sometimes as strangers at a party, sometimes Toni placed into the Goodkind household as a foster child — a premise that recurs specifically because it inverts the power dynamic and puts Toni inside the machine that was built to break people like her.
The second category is island extension and season-3 fic: picking up where the show left off, either writing through the bunker escape and its aftermath or extending island scenes the show didn't have time for. The lychee tree appears in almost all of these.
The third category is post-rescue and witness protection: the girls are extracted from the experiment and placed in protective custody while the case builds. Shelby has to navigate going home — her father, the conversion therapy group, the world that shaped her — while now in a relationship with Toni. This is the fandom's primary site for exploring what comes after the island's freedom.
The fourth is modern AU without the island: college, sports, the workplace, Toni as a basketball player and Shelby at some remove from the pageant world, trying to figure out who she is without an audience.
The fifth is the "Shelby comes back from Texas" reunion fic — the darkest register, positing a gap after the island where Shelby returned to Texas, slipped back into the performance, married Andrew (her canonical fiancé), and years later encountered Toni again. These fics are about the cost of the choice not to be free.