re: Denia - Masking and performance per audience type.
Denia is a masterclass actor, that's without a doubt - because she has to not only mimic humans to blend in with them, but with her budding humanity, she has to pretend that she is still an obedient, mindless doll in the Fractsidus' hands.
To that end, her acting must fool one and both alike, regardless of who is watching her performance. Among regular people, she has to be approachable, likeable and a person with an actual individual personality - and among her keepers, she has to be a mere tool whose only thoughts, if any, is to fulfill the missions entrusted to her without question.
Of course, the Fractsidus have long realized she isn't the empty vessel they needed - likely the moment she began to voice questions of any kind. Some questions were certainly benign, maybe necessary things for her to ask, in order to advance her missions and thereby the goals of the organization. But others were likely not, even if phrased as a logical inquiry for simply more information to integrate and calculate into her own framework of things.
Curiosity, even if just idle, is still curiosity - only someone who thinks, who wonders, who doubts, will ask questions.
And it's possible that this outcome, while not intended, was within expectations nonetheless - a way to heighten her resonance with the void. Because nothing defines nothingness, or rather absence, more than the loss of something that once filled the emptiness.
Hence, the Grand Architect's not-subtle threats and comments on her "usefulness", in addition to the occasional dismissive tone for Denia's words (sentiments) and behaviors (depression and mania, when rarely expressed and noticed) alike - which, besides being psychological manipulation to further their project with her, also indicate their awareness of her individuality. And the fact that they are, as such, purposefully agreeing to let the matter go and play along, essentially.
Which would make her attempts to mask around the Fractsidus quite useless... but likely, Denia maintains this image of an mindless doll in front of them to some extent anyway - out of longstanding habit, and out of fear of pushing this unspoken boundary too far. Because even if they know she can't be a perfect vessel anyway, they're still using her rather than discarding her. Which means she is still meant to do something for them.
Which means she still needs to play a role. as long as there's an audience, as long as someone—something—is watching, she needs to wear the appropriate mask and act accordingly.
All the world is a stage, indeed.