Creator Breakdown: The movie was inspired by an incredibly messy divorce that Andrzej Żuławski was going through in the late 70's, as well as his increasing estrangement from his home country of Poland. The experience of filming it, in turn, caused both of the leads to have this. Sam Neill described it as "the most extreme film I've ever made" and said "I only just escaped that film with my sanity barely intact", while Isabelle Adjani took years to recover from the role emotionally, even attempting suicide soon after seeing the completed print.
The same infamous subway scene would later be referenced in The First Omen where Margaret loses control of her body after a car accident, during which her pregnancy with the Antichrist progresses to the birthing stage in a little over a minute.
Troubled Production: The film was a personally devastating film for Andrzej Żuławski and its lead actors. The film was inspired by and written during a traumatizing divorce Zulawski had from actress Malgorzata Braunek, combined with receiving a de facto ban from his native home of Poland, that left him in a deep depression. Zulawski hoped to use Possession to address that depression, and put Sam Neill and Isabelle Adjani through an utterly hellish filming experience, ostensibly in the name of drawing the most emotionally extreme performances out of the two. Neill would later say "I only just escaped that film with my sanity barely intact", while Adjani outright attempted suicide after seeing the premire, and needed several years to recover from her performance in the film.
For the book by A.S. Byatt:
Viewers Are Geniuses: Cropper maintains Randolph's belongings in "the Stant Collection" at Robert Dale Owen University in New Mexico. "Stant" is a gag on author Byatt's part referring to a woman named Charlotte Stant in a Henry James novel, The Golden Bowl. Living in Europe, she is actually bought and paid for by Adam Verver, an American millionaire who wants to be her husband. Byatt thinks James was trying to portray both the advantages and disadvantages of having wealthy people collect things to preserve them.
Byatt may have intended a university in Utah named for Robert Dale Owen to indicate people and things that are not at all where they belong; Rep. Robert Dale Owen (D-IN) (1801-1877) belonged to the great state of Indiana. His temperament is suitable to the story though, as he was an ardent feminist, abolitionist, spiritualist, human rights activist, Commune co-founder (now the town of New Harmony, Indiana) and Democratic Socialist, who sponsored legislation creating the Smithsonian.
"I only just escaped that film with my sanity barely intact", while Adjani outright attempted suicide after seeing the premire, and needed several years to recover from her performance in the film.