'The Replicated Man' in Fallout 3 we get introduced to the 'synths' and I wonder what the synths really are.

I always thought of them as being a miniaturized (compare to the ZAX supercomputers) Artificial Intelligence which was connected with an anorganic skeleton and organic replications of flesh and blood (essentially the same as humans have, only combined molecule for molecule). The artificial brain as the main processor controls all manners of lifelikeness by its combination with a synthetic nervous System.

Of course there would have been a long road of scientific progress that finally led to the creation of such a sophisticated synthetic human as A3-21/Harkness. The first step was probably the development of true artificial intelligence (perhaps the Institute tried to mobilize the ZAX intelligence and tried to upload it on smaller devices or emit it's processings into a recipient) which then got transferred into a mobile, robotic client. They now had to smoothen its motions, make it more lifelike and resembling true humans, while transcending the uncanny valley and the possibility of (non-)sensations beneath the human capabilities to mentally handle. Of course this probably all was an effort that would lead to the final possibility to practically immortilize people by transferring their organic brain into such a body that was capable of feeling like a real body feels. The AI was the test subject.

Of course even A3-21 isn't perfect. He still can be programmed. He's still infertile (as we can assume without any proofs). And although people automatically assume that the Institute made him follow them, it could be equally possible that he did so voluntarily at first, until he realized the doom he brought over beings that like him could feel.

Which would bring us to the point of why the synths are 'enslaved' by the Institute. I think they weren't created to be hard working labor slaves. But first let me hear what you think a synth really is (bashing is welcome)

Synthetic human. Like Bishop in Aliens that is what a synth is.

It's the principle of Our Androids Are Different. What differentiates androids in Fallout from any others?

As far as I can tell there is none. The Developers of Bethesda watched Blade Runner and thought they would throw it into the Fallout Universe.

My personal head canon is that they're actually augmented humans enslaved by the Institute, who uses the "android" bit as cover for their human slavery operation.

There's absolutely no basis for this of course, but I like it better than Fallout: Blade Runner.

I agree 569%. The "synths" should be brainwashed mind altered and cybernetically enhanced humans.

The interesting thing is that Fallout already has a history of using organic brains in robotic bodies. Does anyone here remember the concept of what transpired on the Cygnus in the movie 'The Black Hole'? It's where Dr.Reinhardt had converted the entire crew into drone workers... Such could be done in Fallout's setting; similar, but not the same, where the androids are partial or total conversion cyborg humans with lobotomized brains; (lobotomy being rather popular in the 50's era, so that's sort of a stylish plus as a side effect).

There was also an interesting Twilight Zone episode, where a company offered synthetic youthful bodies for sale; and would transplant the mind into one. In the episode, and aging couple sought to reclaim a youthful existence as young advlts again, and the husband tried the service demonstration ~returning as a 35 year old athletic version of himself... But they found out that they could not afford two bodies on their life savings, and so rather than the man getting the procedure, and gambling that he could work [for years] to be able to eventually pay for his wife's transfer, they decided to stay as they were; together.