Warning: Spoilers for The Last Jedi
We first meet Rose in a private moment of grief, only a few hours at most after her sister's death. An engineer on the resistance's flagship, Rose isn't a hardened fighter on the front lines like her sister, but she takes her post seriously and actively defends her ship and her rebellion. The resistance, or rather its mission to free people from oppression, is all that matters, and she pushes her grief aside to do her job.
When she and Finn come up with a plan to escape the First Order's fleet, there isn't even a moment where we think she might back down from facing the danger herself - again and again in the movie, Rose is inspired by her sister's sacrifice and her belief in the Resistance, throwing herself into circumstances that she's probably not trained or adequately prepared for. But as the resistance grows smaller, everyone needs to step up, and Rose is at the front of that group every time.
She sees past the facade of Canto Bight because she's familiar with its real ugliness; it's her grounded optimism that ultimately gets her and Finn out of danger - she knows how powerful the rebels' symbol is and what it means to people like her. The first time I watched The Last Jedi, I thought this whole sub-plot would be easily removed from the story, but it's the bit that's stuck with me the most. This might be the first time a Star Wars film has shown us life in its galaxy, on a planet that's not a dirt-farming market economy, military base or Tatooine - and it's long past due for the series to show us what, exactly, the rebellion is fighting for, not just what it's fighting against.
And that's importan, as the franchise passes the torch onto its new generation. Rey, Finn and Rose are nobodies, orphans who through choice - and no small amount of luck luck - find themselves in a position to make a difference. They didn't come from a space wizard bloodline, or from nobility. They have no part in this story, except for the ones they carve out for themselves.
At the end, the Resistance leadership's faith in the powerful allies they thought they had is shown to be unfounded, their calls for help going unanswered as the First Order kicks down their front door. But Rose's faith in (and dedication to) the downtrodden and the oppressed, might just point the way to an ultimate rebel victory.
Even more than Rey, Rose stands in opposition to Kylo Ren's "kill the past" ethos. Rose's past gives meaning to her present - a childhood in poverty led directly to her joining in the resistance, where she tries to lift the entire galaxy out of the cycle of exploitation she experienced as a child. It's easy for Ben Solo, the son of two generals (one of them royalty) and heir to the Jedi legacy, to throw away the past he's taken for granted - but for the people who had to fight for what they have, the past is a constant reminder of what they can, and must, do better.
That's how we're going to win. Not fighting what we hate - saving what we love.