Prequel

 The prequel, film & literary work, is unlike anything people expect, & is told solely from the perspective of PHYN (Adam Driver type) with events that lead to Beladi leaving him (as told in the first book/film). It has not been written, yet there is a solid sense of the progression of the story. None of it can be given away here.

Sequel

 The sequel, both film & literary, take place a year after Beladi has started her new relationship with River. Neither has been written. None of it can be given away here.