scifi species idea: species that has three sexes resulting in humans eventually adapting their third gender's behaviors as a form of nonbinary identity/presentation. the plot twist is that the alien civilization already has nontrinary identities and now some humans start identifying as nontrinary too. this leads to a space war between the nonbinary and nontrinary factions of humanity, absolute chaos, alien civilization obliterated in the crossfire. it's a metaphor for something, how we appropriate stuff I guess, let the fans figure out what it means.