The fact that Pipp followed a bunch of strangers she has heard Only Bad Things about because her big sibling said 'I think it's worth it. Please come with us.' (granted the both of them were under pressure and it was either Go or Risk Getting Arrested, but like she didn't HAVE to stay with the group) She's scared and she was just humiliated on live TV and even though Zipp completely left her hanging, she still goes to her big sibling 'cause that's who she wants to be near when everything is falling apart. She's angry and upset, but she makes a point not to leave her sibling hanging by bringing that stupid gem with her when she demands an explanation. She loves her big sibling, she refuses to believe Zipp would do something so hurtful without a damn good reason. She's known Zipp her whole life, and right now Zipp is all she has and She Will Not Just Quietly Let Her Go.
Zipp marvelling privately to herself at how Pipp can do Any Of The Things She Does. How she can live such a public life, how she can be so classically emphatically princesslike as though she was just born that way and enjoy it, how she can keep up appearances so well and go with this lie their family has been keeping up for generations. Zipp sees Pipp and she sees this fluttery soft ball of feathers and sparkles, but she also sees herself. She sees her own determination and conviction, but what Pipp is determined and convicted to do is be the Model Princess. To be the person that lifts the spirits of those around her and inspires them to comfort and love and assures them nothing is wrong, everything's okay, you are wonderful and I appreciate you. It just makes Zipp so weak to think about and she almost doesn't know what to do with herself over it.
The way Zipp brings out the imperious uncompromising bits of Pipp and Pipp brings out the delicate soothing bits of Zipp. The way they're irrevocably connected to eachother. Even the feathers of their wings contrast and they don't seem like they could possibly be related at first glace, but they look at one another and there's unconditional trust and an unbreakable connection that cannot possibly come from anyone but two people who call one another 'sister'.
Zipp placing a little sticker over top of Pipp's camera lens when they sneak off for a date because she knows Pipp compulsively posts Everything and cannot keep a single thing to herself, so the best solution is to just tell her not to say where they're going and keep her from taking pictures in case someone decides to triangulate their location to mob Pipp for parasocial attention or something. Pipp bringing Zipp breakfast in bed because she knows Zipp can't wake up early enough to eat a proper breakfast before the day goes into full swing to save her life, and she knows Zipp is always in a better mood when she brings a quiche and good morning kisses to her.
I could go on, but that's plenty of paragraphs I think,,,,,,