Let's talk about the kids swearing fealty to the Black Swan.
The oath is "I will do everything in my power to help my world." You have to truly mean it for the box to open.
Sophie gets it in one. Fitz gets it in two. Dex and Biana get it in three. Della gets it in four. Keefe gets it in... well. It was a lot. And he'd prefer not to say.
And I think that with all of these numbers, the issue comes down to one of motivation rather than commitment. Keefe's struggles present a very good example of this.
I think Keefe initially spent too much time dwelling on the "everything in my power" part of the promise. He keeps saying it, over and over, "I will do everything in my power to help my world," and he doesn't understand why it's not opening. He's committed. He will do anything. His mind keeps racing over all the reckless plans he has, the way just a few pages ago he told the Collective to just give him a green leaping crystal and send him to Ravagog to take on the ogres single-handedly as if that's not the dumbest idea ever to cross someone's mind. He's willing to do absolutely anything and increasingly wilder, more reckless scenarios run through his head as he thinks about everything he's willing to do, how he wants to do everything in his power, more than the Black Swan will even let him do, they're saddling him with books how can he possibly mean this oath less than they do when clearly there's more in their power that they can be doing--and I think it takes a while for him to pay more attention to the second part of the phrase: "to help my world."
Because if he really finishes the phrase the way he really, truly, deeply, recklessly means it, it comes out to, "I will do everything in my power... to save Sophie. To keep my friends safe. To get revenge on my mom. To be better than my parents. To stop my mom. To get avenge Sophie and Dex for what the Neverseen did. To prove the Council wrong. To stop my mom." And an ongoing list of reasons along those lines.
So he has to pause and really think about what it means to help his world. And whether he's willing to do everything in his power to do that. Even if that means something he wouldn't like about his ability to achieve those other motivations... his anger towards his mother, his resentment towards his family and the council, his love for his friends, his care for Sophie... will he do whatever it takes to help his world? And I think once he starts meditating on that aspect of the oath, it still takes him a few tries, but it calms him down, makes him think, and ultimately that's what he's dwelling on and what he's redirected his determination towards when the box finally clicks open.
Sophie gets it in one try. She is the only one to get it in one try. With Sophie, neither parts of the oath present an issue. Not only is she willing to do everything in her power, something her determination and occasional recklessness througout the prior books has demonstrated, but she also has the most complete understanding of what it means to help her world out of anyone who swears fealty in this chapter. She can claim all of it, the elves and the other "intelligent species" and the Lost cities and the Forbidden Cities, the many many many Forbidden Cities, the large part of the world taken up byhumans, as her world.
The elves spend so much time attempting to pretend humans don't exist or othering them as something horrible that even people like Dex, Biana, Della, and Fitz might have at least a small hurdle to get over in the way of claiming the whole world to be their world. The words "my world" have to sincerely and entirely include the whole world, a large, large part of which includes humanity, and Sophie is the most thoroughly aware of that. Humanity was her entire upbringing. She cares about her own race as well, and every time she meets a new race of creatures she seems to care for them as well as soon as she learns they exist, because her hurdle to understanding them was one of pure ignorance, rather than systemic exclusion. So when she says "I will do everything in my power to help my world," every part of the sentence has the right commitment: she will do everything in her power. And it will be for the good of her entire world. And no matter what part of it is in danger, she will do everything in her power.
Fitz is a close second to Sophie, only taking two tries to open it. While he still faces the common elvin hurdle of needing to really think about what his world means and all that includes--but he was searching for an elf living among humans in the Forbidden Cities since he was six and canonically took a souvenir from every Forbidden City he visited. He knows at least one of their languages (and I'm guessing more than that--if I were his father I'd make sure he learned English, Mandarin and Spanish before walking into the Forbidden Cities searching for a kid) so he also has an easier time merging his understanding of his world with the larger world.
Then comes Dex and Biana--who again, don't exactly take forever, just one more try than Fitz. They're not as closely connected to the human world as Fitz, and definitely not as much as Sophie, and since humans inhabit so much of the planet that also poses a minor hurdle for their elvin minds, but they can get past that. Dex finds human technology fascinating and grew up on human movies. Biana's brothers have human clothes in their closets from their secret missions, which she now knows about, and Sophie is one of her closest friends--one of all of their closest friends, which also broadens their minds and their understanding of what their world means. And lastly, there's Della, who only takes one extra try, influenced to not take too long by a lot of the same things that made it easier on Fitz, Biana and Dex, but also not as easy because of how much older she is and how much time she spent socialized by the Lost Cities during a different era.
I think it's especially interesting because you would think--and I think they all initially think--that the stumbling block to being able to truly mean the words would be willing to do "everything in your power" because that's a huge commitment. But the thing is, these people all just abandoned their lives in the Lost Cities, cut their pendants, and went into hiding to join a rebel group because of their determination, most of them after having participated in a Black Swan ambush for the Neverseen only a few days prior. No one in this group is struggling with the idea of committing to doing everything they possibly can to help. It's the understanding of what they're helping--what their ultimate goal is--that holds all of them back for a moment.
All of them except Sophie, hidden among humans by the Black Swan because they saw the importance of having such a perspective.
And most of all, Keefe, but not for any reason that has to do with claiming the entire world as his or a willingness to open his mind to the importance of humanity, but rather because he's the most lost out of all of them, the most damaged by recent revelations, and it's messing with his sense of motivation. He's holding on too extremely tight to his attatchments to his close friends and his anger at his parents and the neverseen and his mom and his desire for revenge or even just a desire to be useful and helpful for his motivation to properly settle into the determination the Black Swan needs from him, which is the motivation to help their world.
And I have a stamp of appreciation and approval from @autistic-daydreamer on this Keefe opinion which I consider extremely important
