I still think that there are some things that I need to understand about this Black Numenorean Bilbo becoming The Mouth of Sauron idea before I feel I can like it. ...
Back to the first idea, he suffers from memory loss. He's turned into some kind of robotic version of a man (not with cyborg machinery, just without a free mind). If we want to go this way, I suggest that the antagonist of this season's frame, the female Mouth of Sauron, displays similar flaws. She should be a puppet, her strings pulled by Sauron, someone who doesn't know her own identity. Perhaps someone in the story knows her real identity but it's clear that she has left it behind years ago. If we do this, I think it could work. Ok so I've talked myself into supporting the idea.
I definitely like this idea!
One of the key details about the Mouth of Sauron in the text of RotK is that he has no name of his own, and has perhaps even forgotten it. That detail, however, is in the narration, not the dialogue. When we get to that part of the story, there will be no straightforward way to convey that onscreen. We can't just have someone say, 'by the way, no one knows this guy's name - he doesn't even know it himself!' Sure, he can introduce himself as the Mouth of Sauron, but beyond that, how will we show the loss of identity? One of the clearest ways...is if the audience has seen him in his pre-Mouth of Sauron days, and can see the stark loss of identity for themselves (though obviously, few would recognize him or realize who he is, so it's a rather subtle way to include that detail).
Showing that now, in this frame, with the 'original' Mouth of Sauron/high priestess...that will establish a parallel. That way, we will see the possibility. If we see our 'Bilbo character' go from Gandalf's pupil to the Mouth of Sauron's pupil, we can guess about the effects of that choice...but when he rides out of the Black Gate in 70 years, it will be more stark. So, yes, I do agree that the Mouth of Sauron character in the Frame needs to be giving the 'pretty speeches' that Gandalf mentioned in his conversation with Saruman, but also we should portray this person as someone consumed by the role, lacking a personal identity. I think that's a very good angle to take. And perhaps we will even find an opportunity to comment on that in this frame, as we do have several episodes focused on identity and choice - from Bëor moving to Nargothrond, to the Council of Estolad, to Andreth and Aegnor's failed romance.
One of the things that Corey Olsen discussed was how Sauron needs to corrupt Men to get them to not only join his cause, but to march in armies alongside Orcs. That's not just a matter of swaying someone's political opinion - that is a whole process of corruption, which has steps like human sacrifice along the way. In this frame, we are at the early stage of that corruption; the high priestess is not sacrificing political opponents on an altar...yet. Showing the beginning of the corruption of Gandalf's friend, and the 'end stage' corruption of the priestess who has lost her own identity and merely parrots Sauron. . .that is the story we are trying to set up here, I think.
