They both go through a series of different emotions related to their situation, Mark's which is generally obsessive about learning why Anna, who he still loves, wants the divorce, and Anna's which is generally increasingly histrionic in getting away from Mark.
Two houses in the film — the modern one, which is Mark and Anna's apartment, and the old abandoned house in , where Anna hides the squid-like creature — are located next to the Wall.
Over and over, for 123 minutes.
In the beginning of Possession, they meet and try to explain to each other, in a relatively calm fashion, what's happening.
But the best compliment one can give the film is that it's a complete original.
Mark visits and fights Heinrich, who beats him.
Warning: watching Possession will probably make you feel like you're losing your mind.
I sense no cinematic influences though there is some thematic overlap; Cronenberg's The Brood comes to mind , no trends being followed.