I'm curious what the long game is with Mariner. What makes her compelling to me is her annoyance at everyone pressuring her to rise up the ranks when she just wants to be good at a job she enjoys. All her superiors dump on her for lacking ambition when she "has so much potential" (CRINGE), so she actively sabotages herself to avoid getting promotions she doesn't want. I definitely relate, I have a job that I don't love but was previously fine with and good at, until they pigeonholed me into supervising a ton of people and now I get in trouble if someone else is bad at their job. I'm not a leader, I hate leading, and now I'm desperate to find something else.
So I'm kind of paranoid about what side the show itself is actually on, whether everyone needs to lay off Mariner and let her stay unambitious and happy, or whether Mariner needs to step up and be fine becoming an officer. They have said the plan is to show these characters progressing, but I have no idea what that looks like with her. It's the central conflict of the show, imo, and I'll be very disappointed if it ends with Mariner as a captain but, like, one of those cool ones.
The question is a compelling one, particularly for a setting like Star Trek where no one needs to work. When no money is involved, reputation and authority are the only currencies that matter, and so anyone who joins Starfleet but doesn't want one or both of those things will be looked on with suspicion. I just hope that this show about the least important people on the least important ship comes down on the side that ambition is great, but lack of ambition is fine as well. Mariner's flaw is that she does reckless and even childish things to stay in the lower decks, not that she wants to stay there.
I'm sure there's a solution here and an ending for Mariner that's true to her character, and the writers have shown so far that they know how to handle these characters. Here's hoping they're able to thread that needle.