Ok. But Syd is begging the child version of David's psyche to wake up. "Babe, if there's any of you in there, you need to wake up now!" I believe, though that's from memory and I could have wording wrong. And then... SHE wakes up in the "real" world. Something she should have no control over, given the powers in play from David and Ptonomy.
Except she and David have switched bodies, and I think the conversation where David talked about retaining some sense of being Syd was meant to set up the idea that Syd retains some things from being David -- an idea that was confirmed when she saw the Demon that only David could see before. Given that, it stands to reason that she could wake herself up because of that residual connection.
I'm not saying you're wrong about things being real. I actually agree that much of what we're seeing is probably more or less "real" at face value. But you're the one assuming that any of this is "the real-world present", when the show has actually done nothing to suggest that is the case.
No, I'm not assuming, I'm reasoning. At this point, the model I find most consistent with the available evidence is that what is being presented as real is probably real. I do not assume that
must be the case; I am not emotionally attached to it or resistant to changing it. It is merely my tentative working model at this moment, subject to change as new evidence is presented.
In fact, if anything, it's regularly displayed that David is an intensely unreliable narrator. Through no obvious fault of his own, but there it is. We're SUPPOSED to be questioning his sanity, and his reality. The character himself even asks the question in this latest episode. What if he isn't sane?
Of course, but questioning does not mean taking it for granted that everything is false and nothing can possibly be known. It means reasoning it out with an open mind, observing the data and making deductions from it. There are patterns in the noise, and even with an unreliable narrator and a confusing viewpoint, there does appear to be (note,
appear to be) a distinction emerging between the scenes presented as "now" and those in David's mind and memory. The other characters are aware of things that David isn't (for instance, we've seen "Kerry" get absorbed into "Cary" but David is still apparently confused about who Kerry is, and we saw Amy getting interrogated by the bad guys before David mind-teleported and discovered she was being interrogated), and he has things going on in his perceptions that are separate from them and what they're aware of (e.g. Lenny).
Also, if all of this is strictly in David's head, why is he only now learning concepts that never occurred to him before, like the existence of mutants and the idea that he has powers? If everything that's happening is just in his head, where did the new ideas come from? There must be
something external to catalyze the change.
I also challenge your assertion that the drama would be unsatisfying if only David were real. End of the day, it's fundamentally his story. And if they're all just aspects of him, then he's working things out inside himself in a really, really literal way. But that doesn't in any way undermine the critical relationships, it just changes their configuration.
But there are no relationships if there's only one character. A relationship is between two or more different people. We're a social species. We care about interactions, not a single person's self-absorption. We need there to be stakes and risks for dramatic intensity, and if there's only one character in the show plus his delusions, then we know he can't be killed or the show ends, so there's no real danger to anyone. Also, what about the future of the show? How long could it sustain a narrative that was entirely hallucinatory? How long could these characters remain part of the narrative, and their actors remain employed on the show, if they were unreal? How would they grow? How would the narrative grow and broaden in scope over time if it were all inside one guy's head? I just don't see that kind of story sustaining itself as an ongoing series. A movie, sure, but for long-form storytelling, it seems unlikely to me.