This post contains spoilers for Dune: Prophecy episode 4 and details from the book Dune Messiah.In the final minutes of Dune: Prophecys fourth episode Twice Born, Valya Harkonnen (Emily Watson) feels a twinge of doubt about her mission. However, she recovers her resolve when she faces her beloved older brother Griffin, whose death decades earlier inspired her revenge quest. Griffin speaks words of reassurance, even when Valya asks if she pushed her brother too far.As the conversation reaches its conclusion, Griffins face begins to crack. Thank you, Theo, says Valya, who then watches what appeared to be her brother walk away. As he moves, he transforms into a taller, older male-presenting figure and then into a shorter Black woman. In that moment, we realize that Theo is Sister Theodosia (Jade Anouka), the acolyte who came with Valya to Salusa Secundus.Even newcomers to Dune understand that Theodosia is some sort of shapeshifter. But in Dune terms, Theodosia is a Face Dancer, a key part of the Frank Herbert novel Dune Messiah, which Denis Villeneuve plans to adapt as Dune 3.Face Dancers are a creation of another group mentioned in Dune: Prophecy, the Bene Tleilax, the patriarchal society that practices genetic engineering. Those practices led to the creation of Face Dancers, asexual and servile shapeshifters who perform a variety of functions within the Imperium. Often, the Face Dancers provide forms of entertainment for citizens in the Imperium, but they can also serve as spies and assassins.In fact, thats how Face Dancers are introduced in Dune Messiah. Picking up 12 years after the end of Dune, Messiah deals with a conspiracy targeting Emperor Paul Atreides, whose Fremen Jihad has intensified his enemies anger against him. That conspiracy includes expected members, including Irulan, Pauls legal wife and daughter of the previous emperor, and Bene Gesserit Reverend Mother Gaius Helen Mohiam, as well as Scytale the Face Dancer.As has been commented many times since its initial appearance in Galaxy Magazine in 1969, Dune Messiah is a much knottier book than Dune. Not only did Herbert make Paul a much more unlikable character in Messiah, part of his goal to underscore a mistrust of charismatic leaders, but much of the action happens off the page, with more of the books attention devoted to palace intrigue and secret plots, not unlike Dune: Prophecy.However, Scytale brings some dynamism to the storyline. The book opens with Scytale assassinating a Fremen leader and then sneaking into Pauls court in the guise of a trusted figure. Its no wonder that David Lynch counted Scytale as one of the elements that most intrigued him about adapting Dune Messiah for Dune II. In fact, he already began seeding that part in his take on Dune, as the next movie would have revealed that Baron Harkonnens doctor (played by Leonardo Cimino) was Scytale in disguise.Given that it takes place 10,000 years before Dune Messiah, its hard to draw too many connections between the book and Dune: Prophecy. However, the appearance of a Face Dancer among the acolytes does shore up one of the shows major theories. Like the Bene Gesserit, the Bene Tleilax havent reached their full power yet, and thus they do not quite have the same rivalry with the Sisters as theyll develop. However, they do have their own goals, and arent above giving their creations as gifts to enemies to strengthen their positions.In fact, thats probably whats happening with Desmond Hart (Travis Fimmel), who may be twice born because hes a ghola created by the Bene Tleilax. He could be working for Emperor Javicco (Mark Strong) as part of a Tleilaxu plot to gain power, something the Emperors too dense to realize.Valya might be smarter than Javicco, but she is blinded by her anger. So although she knows that Theodosia is a Face Dancer, and knows that Face Dancers come from the rival Bene Tleilax, she believes that she can out with the manipulators. At least, thats what Paul thinks when a ghola of a beloved friend arrives in his court in Dune Messiah to mixed results. Is Valya smarter than Paul Atreides? Well find out as Dune: Prophecy airs its final two episodes.Dune: Prophecy airs Sundays at 9 p.m. ET on HBO and Max, culminating with a finale on December 22.