A video of new Game of Thrones cast members was released at San Diego Comic Con last week, featuring the faces of new characters including Doran Martell, some of the Sand Snakes, and Trystane Martell. But notably missing was Arianne Martell.
Arianne Martell, for non-book readers, is the eldest child of Prince Doran and the heir to Dorne. Although Dorne is the one place in the Seven Kingdoms with absolute primogeniture, meaning the eldest child inherits regardless of gender, Arianne finds evidence that her father means to ignore her inheritance in favor of her younger brother, and becomes determined to defend her right to rule. She's also described as having "olive skin," making her, along with the other Dornish, one of the most prominent non-white characters in the series.
And her absence from the casting video shouldn't be totally shocking. I doubt they've finished casting the entire season yet. Except that, in the casting press release, they describe Trystane as "heir to Dorne," suggesting that, even if Arianne somehow ended up in the series, she wouldn't be the character she was in the books. At best, she could still be Trystane's sibling, attempting to supplant her brother with her schemes -- either as an elder sibling who was overlooked, or as a younger sibling who wants more power than she has. That, at least, could lead to an interesting plotline. At worst, she's been deleted entirely and her Myrcella-related plotline given to Trystane. Either way, it's hard to imagine a greater irony than Trystane being declared the heir to Dorne in the show, when Arianne's entire plotline is about her fighting the possibility that her brother will be declared heir instead of her.
In the show's defence, most of Arianne's significant actions could be given to someone else to streamline the plot. The only way her storyline has affected the other players in the series, at least so far, has been its impact on Myrcella, and it would perhaps be simpler to give that story of Myrcella's betrothed. But this isn't just a problem of whether the plot can still make sense, or whether the audience can remember yet another new character name. They've erased a competent, defiant, influential female character of color, and replaced her with a white male character. They're taking away a female character's fight for power that is rightfully hers, and handing that power to exactly the sort of character she fears will take it from her, assumedly for the very reason she fears she will be overlooked. Not only that, but if they erase Arianne's role in the Dornish plotline, they're erasing one of the few fantasy plotlines where a female character fights for (or manipulates, depending on your perspective) another female character, to win them both more power. Even if the storyarc itself is given to Trystane, that very compelling element will be lost.
I probably shouldn't be surprised, given the show's track record of misinterpreting and ignoring female characters and minimizing any hints of diversity. But this is, I think, the first time a highly significant and influential female character has been erased altogether. And since Arianne's storyarc has lots of room for both big dramatic moments and ample nudity, two things the show seems to love, I can't help thinking that both sexism and racism played a part in deciding that Arianne was better off as Trystane.