Your frustrations with Mal and Simon’s dynamic are so true! Mal keeps thinking he knows Simon’s character, and where he will choose to be selfish (choosing his sister and safety over the crew’s, maybe going back to the alliance planets) and where he will choose to be a selfless doctor/break the law. I always thought it was because Simon himself is changing through the events of the show, having to adapt to this new life, and even he doesn’t know where is morality is at at the moment. He’s unsure of what he’ll choose as well !
oh to be clear i love this about them lol; mainly, i think it's very frustrating for mal.
and yeah, simon is changing and having to figure out what his worldview is and how he'll react in a given situation because the life he's living now is so categorically different to anything simon's ever experienced before. i also think (and i have a longer post i want to write soon about this) simon doesn't quite realize it but is living in a near constant state of hypervigilance and survival mode and just like, Is Not Actually Doing Too Hot, imo, basically since he got river's letters but ESPECIALLY since rescuing her and boarding serenity. and when that's the state you're living in, your reactions to things and way of functioning is... not always that consistent. it eases a little after the pilot and a little more after safe but uh. i'm not convinced we ever see simon one hundred percent Out Of that state until maybe the end of the film, because the tragic thing is he really does have reasons to be as worried as he always always is.
ANYWAY. all this to say big agree, i think it's also having to constructa a worldview and identity in real time and not quite knowing what he'll choose, either, like you said, which is why the simon who immediately rolled up his sleeves to help the sick in jianying even though he'd been kidnapped is also the simon who plans a whole heist to steal from a hospital and the simon who drugs jayne against his will is the same simon who assures him he'll never harm (well by his own definition) on his table. truly the king of compartmentalization imho.
