As with Vertigo, there is, additionally, substantial narrative overlap between the two films, as Robert from The Film Experience notes astutely:

Both are about two women living together under unusual circumstances, one sick, the other a caregiver. In both cases, at least one of the women is an actress. Both films show a general degredation (sic) of these women’s relationships…Persona begins with actress Elizabeth Vogler (Liv Ullmann) experiencing a sudden fit of despair and going voluntarily mute. In the hospital, she’s paired with nurse Alma (Bibi Andersson) and the two are sent off to a seaside cottage where they develop an ambiguously intimate relationship… Eventually the film begins to flip on it’s head, revealing its own artificiality, and it becomes impossible to know who is who, and what role they’re playing. Mulholland Drive opens with aspiring actress Betty’s discovery of accident victim amnesiac Rita hiding out in her apartment. Soon, between line readings and Betty’s audtions, the two lady sleuths are investigating Rita’s life and identity and eventually becoming lovers (or have they always been?). Eventually the film begins to flip on it’s head, revealing it’s own artificiality, and it becomes impossible to know who is who, and what role they’re playing.

Add to this list another essential similarity at play: the arc of the characters of Alma and of Betty/Diane. Alma’s evolution is conventionally summarized as a slow merging with Elizabet’s personality, but I believe that what actually happens is much more subtle than this. A fuller description of her arc would emphasize radical and fundamental changes in her persona rather than simply find a slow consuming of her will by Elizabet’s. It is true that, early in the film, Alma suggests to the hospital administrator that Elizabet be paired with a more experienced nurse because she worries that she, Alma, will not have the mental fortitude to engage her willful patient. It is also true that such concern turns out to be prescient, since, as Robert notes, “the silent, passive judgement of Elizabeth begins to turn Alma into an aggressor.”

Like Mulholland Dr., and Vertigo both, Persona is the story of a betrayal, and an investigation into a power dynamic. Roughly midway through the film, Alma opens one of Elizabet’s letters without permission and discovers that her mute companion, with whom she has shared intimate personal detail, has secretly been judging her all along.

“My dear, I could live like this forever. Silent, living a secluded life, reducing my needs. Feeling my battered soul finally starting to smooth itself out. Alma takes care of me, spoils me in the most touching way. I believe that she likes it here and that she’s very fond of me, perhaps even in love in an unaware and enchanting way. In any case, it’s very interesting studying her. Sometimes she cries over past sins. An orgy with a strange boy and a subsequent abortion. She claims that her perceptions do not correspond with her actions.”

Elizabet’s letter, with its aristocratic, clinically condescending take on Alma’s desires, also exposes a class tension between the two women that had not yet emerged obviously into their interpersonal dynamic.

Ebert reads Alma’s subsequent, violent reaction to the betrayal as a straightforward professional failure:

In the sunny courtyard of the cottage, she picks up the pieces of a broken glass, and then deliberately leaves a shard where Elizabeth might walk. Elizabeth cuts her foot, but this is essentially a victory for the actress, who has forced the nurse to abandon the discipline of her profession and reveal weakness.

I’m not sure, however, that Elizabet’s ‘victory’ is so clear-cut. Yes, Alma’s fear is realized, and yes she does abandon her professional discipline by surrendering to a desire toward cruelty. But Elizabet also reveals weakness of her own in this moment, with an involuntary exclamation upon stepping on the broken glass, thereby breaking her own vow of silence — and thus her own code of discipline. In fact, watching the scene in its entirety, it is actually very difficult to reduce into simple terms who its “winner” and “loser” are:

This pattern recurs and deepens throughout the film: Alma, filled with anger, confronts Elizabet over the betrayal, demands that her patient speak, and even threatens to pour boiling water on her. Elizabet replies with her first words of the film, nearly an hour into its running time:

This scene doesn’t end with obvious winners or losers, either. Both Bibi Andersson and Liv Ullmann offer masterly, subtle performances throughout Persona, but this scene in particular is a deeply nuanced exploration of the two women’s relationship. Watch it again; look at their faces. Observe what their expressions communicate, and try to keep track of who is “winning” or “losing” at various moment in their fight—and at what cost.

Ebert notes that Bergman had once told him that “the human face is the great subject of the cinema. Everything is there.” If that sentiment is true for any film, it is inarguably true for this one.

The contours of the women’s power dynamic become more fluid over the course of the movie, as do their identities. It is not clear who is wounded most when Mr. Vogler mistakes Alma for his wife and begins, absurdly, to make love to her in front of Elizabet after coercing Alma to ‘admit’ that she is the mother of Elizabet’s child. And the closing interview between Alma and Elizabet, shot in full first with focus on Elizabet and then in full to observe Alma’s face as she issues her monologue, is a torrent of judgment and reaction.

Alma’s speech exposes personal horror in Elizabet’s life, which provides subtext for her earlier mockery of her less sophisticated caretaker, and seems to upend the earlier balance of power between the two women for good as Alma decisively rejects Elizabet (“No! I’m not like you!”). But then, the film presents a sudden image of the two women’s faces merged together:

Although it is a composite of two attractive faces, there is something deeply unsettling, even uncanny, about this image. This is particularly true for viewers of Persona who have spent an entire film in the company of the women whose faces compose it, and who also encounter this image greeted with horror movie strings. Ebert, again, notes that

Andersson told me she and Ullmann had no idea Bergman was going to do this, and when she first saw the film she found it disturbing and frightening.

Extending this, Wheeler Winston Dixon cites Bergman as recalling that, for