She’s a Four. This is a character who shouts her Enneagram number to the world.
Her passions are large and out in the open. Everyone feels her joie de vivre. She also has that Four stubbornness — remember, for a Four each day has a 50/50 chance to be terrible, so they aren’t dominated by bad times — that we can see when she’s caged in the ship’s hold. She’s a survivor, even through the worst that life offers.
I have a difficult time with Nina in both the show and the books. Her character is fine, but her romance with her captor is deeply problematic. This is a man from a culture that kills her people, a culture that has imprisoned her for being grisha, and she has every expectation that when the ship reaches port she’ll be tortured and put on trial with no hope of reprieve. She can come to see the good in Matthias, that he, too, is a victim of a culture that raised him from boyhood to hate her kind, but not as quickly as she does. The whole relationship is too fast, and it taints my impression of her character. It’s a shame, because she’s brave and loyal. There’s a lot of heroism in Nina, but it’s buried by this cringe-inducing rush to romance.