Solid ideas, RogueLeader. Regarding Rey and the “choice” Kylo gives her, I’d like to be able to emphasize that Kylo thinks the only way they’ll be strong enough to defeat Palpatine is if Rey goes to the Dark Side, just as he did. (“The Dark Side is more powerful!” and whatnot.) Subtextually, this would also be Kylo’s way of validating the choices he’s made this entire trilogy. (“If Rey joins me, and we defeat Palpatine, it will prove that I was right to go down this dark path.”)
So basically, you’d have Rey, who wants to kill Palpatine as a Jedi, but is constantly struggling to avoid slipping into the Dark Side throughout the film. You’d have Kylo, who also wants to defeat Palpatine, but wants to do it through the Dark Side. And you’d have Palpatine, who wants Rey to kill him using the Dark Side, so that she’ll be deep enough into the Dark Side that he can possess her and complete his resurrection.
The Quarters fight could be about Kylo saying “You need to accept it, Rey. This is the only way you’ll be strong enough to face Palpatine. Give in to the Dark Side.” “No!” (This would also, theoretically, come right after Rey’s Dark Side Dagger Vision, if that concept is still in the cards; so the whole scene would sort of revolve around this idea of Rey succumbing, rather than “This is the knife that killed your parents! Ain’t that kooky?”)
Structurally, Finn serves as the angel on Rey’s shoulder, trying to convince her of her goodness (“That doesn’t sound like you. Rey, I know you…”). Kylo is the devil, telling her that she has to submit in order to defeat Palpatine. But when he offers her his hand, she steps back, because she wants to believe that she can still save the day as a Jedi, and not as a Sith. (“I did want to take your hand. Ben’s hand.”) It’s not a clash of goals, but of means and ideologies.
When Kylo destroys the McGuffin in the Death Star, she’s not just mad because he’s made her whole quest pointless. She’s mad because the only way she can possibly get to Exegol now is by joining Kylo on the Dark Side. That doohickey was her only chance of finding Exegol on her own, as a Jedi. And Kylo’s destroyed that chance. You bastard, I’m gonna flippin’ murder you…
Kylo is also torn between the Light, represented by Leia, and the Dark, represented by Palpatine. Maybe Palpatine doesn’t want to possess Kylo because Leia’s influence is still too strong in him or something? (“I sense conflict in you still. You must prove yourself worthy of my Fleet.”)
Thus, Rey’s character arc in the film would supplement Kylo’s, and vice versa. They’d feed into each other and enhance each thematically.
I don’t know if any of this makes sense. My brain is kind of fried from working with the same few audio clips all night haha.