Greg Dorr’s review published on Letterboxd :
I thought I had seen Possession decades ago, but surely I would never have forgotten Isabelle Adjani's apeshit performance.
Right from the start, it's clear that the married couple in Possession -- Adjani and Sam Neill -- do not inhabit the same reality as the rest of us, as they communicate in the most absurdly dysfunctional manner. As their marriage quickly disintegrates, they externalize their emotions in frightening ways, like exhibiting symptoms of drug-withdrawal, cutting themselves and each other, manifesting goopy creatures, and murdering people. Director Andrzej Zulawski strikes the perfect balance between psychological horror and the darkest of black humor. This would make a great double feature with Cronenberg's The Brood for any couple on cusp of separation.
It feels a bit drawn-out at times, especially when Adjani is offscreen, and works best when the two of them are together. All together, however, it's a pretty astounding work of art-house horror with Adjani going completely crazybrains on more than one occasion.