I'm still intrigued about where the writers are trying to take this story, what exactly Desmond Hart is and does, and how it all might connect to Paul Muad'Dib and the events of his time.

Having said that, episode 4 did nothing to explain away or improve upon the things that I brought up in the last two weeks: there are still supernatural shenanigans (from shared visions to microwaved people), and there are still fan service type shout-outs that just break the immersion and world-building of the existing books.

So let's focus on the real head-turner of this episode and discuss what exactly a Face Dancer is and why this one feels out of place based on what we know from the books.

What is a Face Dancer?

In short, a shape shifter created by the Bene Tleilax - a distinct human society within the Dune universe, known for their mastery of cloning and biological engineering.

The first Face Dancer we ever meet in core canon is Scytale, one of the co-conspirators trying to overthrow Muad'Dib's rule in Dune: Messiah.

He alone in this group could manipulate fleshly appearance across a wide spectrum of bodily shapes and features. He was the human chameleon […] The Reverend Mother drew back, and Scytale saw her reassessing him. They were all products of profound prana-bindu training, capable of muscle and nerve control that few humans ever achieved. But Scytale, a Face Dancer, had muscles and nerve linkages the others didn't even possess plus a special quality of sympatico, a mimic's insight with which he could put on the psyche of another as well as the other's appearance.

You might notice that while Herbert uses gendered pronouns, I'll instinctively switch to "it" and "they" because although they can turn into both male and female form, the default settings of a Face Dancer is the human equivalent of a blank slate. From Heretics of Dune:

Almost chinless round faces, pug noses, tiny mouths, black button eyes, and short-cropped white hair that stood up from their heads like the bristles on a brush.

They're sterile, created in the axlotl tanks of the Bene Tleilax, and then raised and molded into whatever function they'll be serving - whether it's entertainment, spycraft or assassination.

Later models even had the ability to take a copy of a (dead) person's memory, enabling the Face Dancers to create almost perfect copies of people.

Why this one feels out of place

My three reasons are: timing, self-awareness and a questionable ambition.

Let me explain.

Timing

While the Schools of Dune trilogy doesn't really talk about the tleilaxu or what they were up to, we do know that only a century and a half before the events of Dune: Prophecy they were selling organs to soldiers wounded in the Butlerian Jihad.

Now according to the marketing material, these organs were the products of advanced biological engineering - the thing the Bene Tleilax tried to be famous for -, but we know that their technology was not advanced enough for this.

What they really did is "recycle" and "refurbish" existing organs they secretly harvested from the fallen.

With the glacial pace any kind of progress or advancement is made in the Dune universe, it seems a bit off that a hundred plus years would've been enough for the Bene Tleilax to not only perfect growing individual organs and human clones, but an organic machine that is capable of perfect mimicry.

Self-awareness

While they can certainly look human (in fact: like any human), I used the term "organic machine" on purpose, because despite Scytale's undeniably high intelligence, what we learn about Face Dancers in the first few books is that they don't have a will, or indeed an identity of their own. They are bound to the Tleilaxu Masters.

With this in mind, it's weird to see Theo/dosia, who certainly seems to know who they are, and what they do and don't want from life. Notably, they didn't want to use their abilities and wanted to simply live as Sister Theodosia, just an acolyte of the Sisterhood.

And this could've been in the cards, as one of the weaknesses of these shape shifters is the complete adoption of a personality, should they remain in the same form for too long. They'd forget that they were ever a Face Dancer and fully believe themselves to be the human they're impersonating.

Obviously that hasn't happened yet - but knowing that Theodosia is Valya's favorite student in the school, I'll have to assume that proper vetting was done before allowing it access to the Sisterhood.

A questionable ambition

But why would it join the Sisterhood?

Being able to blend in anywhere, surely it can't be there to hide out. Does it really want to become a Sister, maybe even a Reverend Mother?

Putting aside the genderless default form and accepting it to be a woman when in woman form, given how it's genetically engineered and grown in an axlotl tank, I'd question whether it'd have a cohesive Other Memory after surviving the Agony.

I can only hope the writers have something good up their sleeves, because I have a lot of questions and none of them lead to anything that the Bene Gesserit wouldn't consider reprehensible.