Previously Andrzej Zulawksi's Possession (1981) was not at all a film I associated with primary colors—presumably like many, I remembered its monster as earthy and its early 80s Kreuzberg as drained of color—but in recent re-viewings I've been struck by the blatant recurrence of a palette of yellow, blue, red, and white that recalls something like Godard's Weekend (1967) or Godard and Gorin's Tout Va Bien (1972).
But my understanding of the significance of this palette has little to do with Godard, however fun it might be to think of a direct influence. Rather, the more I think about it, the more I'm convinced that Possession is a film taking place in the fantasy or symbolic world of a child: Bob (Michael Hogben), the son of Anna (Isabelle Adjani) and Mark (Sam Neill). What we see in the film is a child's subjective angle on his father's absence and return, the breakup of his parents' marriage (something like the negation or reversal of a primal scene), and that breakup's producing the offspring of a monster (who's also in effect the child's brother, and whom—at the end of the film—he doesn't want to let into the house: he may be more afraid of being replaced by his new sibling than by any threat to his body). And then there is also, when his mother leaves the house, the child's symbolic equivalence between his mother and his teacher (both played by Isabelle Adjani). All these primary colors, which are also the colors of Bob's toys, might be seen in these terms.