This whole series is a con. (That's a good thing.)
I went into this book concerned about how it could possibly wrap things up. There were so many loose ends, so many things for Cassel to juggle--his mom, his burgeoning federal government career, his school, and, of course, his love for Lila. How would you tie them off in one book? Answer: You don't, of course. You cut the Gordian knot. And it's so, so obvious in retrospect how much of Cassel character was building to this point, to this final scene. To his confrontation with Yulikova, to his elopement with Lila. There is no way in-universe for him ever to be free, ever to be safe, so the emotional conclusion to the book isn't him solving his problems, it's him accepting their inevitability and choosing how he wants to go.
It's a great case study of how agency is different from power, how you can show a character making their own choices even when all of those choices are bad. The closest literary analog I can think of is Vlad, circa Phoenix. But Vlad's story is cast as a tragedy; he makes his choice as a sacrifice. Cassel . . . well, he knows the Big Score is a lie. He knows every criminal is caught in the end. And so, eyes wide open, he takes the short-term joy that is his best and only option, and he takes it with glee.
And I love him for it.
The romance bothers me less than most YA romances because, in my oh-so-cynical way, I think it's possible to read a lot of ambiguity in it. It's the benefit of a first-person point of view: Cassel's love comes through clearly, but just how does Lila feel about him? How much are her feelings for him tempered by her knowledge that he's the most powerful asset she'll ever have, and his love is the best way to bind him? I think there's some genuine fondness, but I think it would be a disservice to Lila's characterization not to believe that there's a fair amount of calculation going on, as well. Especially in this world of easily manipulated emotions, memories, and dreams. But I'm glad all this is marginal, subtextual. Cassel deserves his moment of joy.