This movie doesn’t explain why Jessica chooses to birth a son rather than daughters as the Bene Gesserit expects. I remember the book, though. (I think, lol.) She loves Duke Leto and wants him to have a son (the patri-lineal monarchy), someone like him, and someone special (if he is indeed the Kwisatz Haderach). Family and love, mothering, are everything to her. This Jessica is very much played with this intention. Ferguson kills it, bringing so much depth to these emotions.
Like Paul, this Jessica is more emotional than the Lynchian counterpart. We see one brief fight moment where she rocks it, but otherwise she doesn’t seem enamoured of the physical realm. The Voice is her specialty, a kind of mind control. She’s going to be either Heart or Head.
I want to say Heart, partly because this Paul is a Four. They really feel like two people against the world, against any of the worlds. Beyond her depth of feeling, though, Jessica doesn’t give us much to work with. Any number can be a devoted mother. When she suggests that Paul needs to go off-world rather than finish the Atreides mission on Arrakis, however, she shows that the personal is more important to her than the political. This would also explain why she births a son, going against the Bene Gesserit plan.
And now I want to say a Six. It’s her sense of duty, of putting Paul in danger with the gom jabbar, even though it’s the last thing she wants to do. Her thinking is black and white: she’ll break the rules for a son, and then follow the rules for the Reverend Mother. Worry, more than any other emotion, consumes her. It’s the fear that Ferguson plays (despite the litany!) that leads me to Six.