Titles
Here's a piece about an interesting parallel between Kai and Nya that I found: how they react to titles.
Nya:
She hates depending on other people and is always trying to be as independent as possible, so she firmly rejects any label or title she's given. And even if she doesn’t necessarily hate most of them, she still wants to be more than that. She refuses to fit into a box when she's actually so much more. She wants to be perceived as her full self and not only the parts of her that are convenient for other people.
Kai:
Kai's self-esteem is very fragile, so when he gets a title that tells him he's valuable, he latches onto it. He craves validation and a label marking him as "good enough" is perfect for that. I believe this is also one of the reasons he was so obsessed with the Green Ninja.
Kai also uses those titles as a shield, a façade to hide his true emotions. Even if they might not be entirely true, he will adapt to fit into each specific box. After all, if he shows people exactly what they believe, they won't bother looking deeper and so they won't notice the weakness and ugliness beneath the mask.
Although as a final note I have to mention that a lot of Nya's titles are demeaning because of misogyny while all of Kai's are empowering.
Both of them have issues with showing vulnerability but while Nya uses her "perfect" image and independence to push people away, Kai tricks them into believing a mask.
