Fans of Dune will be seeing Léa Seydoux in Dune: Messiah. In a post from @badpostseydoux on X, the Dune 2 star teases the return of Lady Margot Fenring.

Now, fans are speculating how Léa Seydoux's character in Messiah will come to be.  After all, the story of Feyd-Rautha & Lady Margot's daughter in the Dune books is different from what's suggested in Dune: Part Two.

Marie Fenring, brought up as an assassin & Bene Gesserit, is killed by Alia Atreides. It is expected that Dune 3: Messiah will deal with what happened since it's part of Alia Atreides' development.

Marie Fenring tries to kill Paul Atreides, but his younger sister, Alia, stops her. Marie tries to kill Paul when she's 6, just five years after Paul becomes powerful at the end of Dune: Part Two. She's friends with Alia, who's about the same age. Marie almost kills Paul, but Alia stops her and kills her instead. Alia gets called “Alia of the Knife” because of it.

In Dune: Part Two movie, Feyd-Rautha and Lady Margot had a child. But what happens to the baby isn't explained. The movie mostly happens on Arrakis, but there's a part where we see Giedi Prime, the Harkonnens' homeworld. We meet Austin Butler's version of Feyd-Rautha Harkonnen, a scary killer who's also the Baron's nephew. Lady Margot (Léa Seydoux), a Bene Gesserit, seduces him.

The fate of Marie Fenring, Léa Seydoux's character's daughter, should be in Dune: Part Three. It ties up a loose end from Dune: Part Two and helps show more about Alia Atreides.