Oh! Not only is this book bad, but it also messes with the established lore and integrity of a beloved 20-year-old series in a way that is truly mind-boggling. I went into reading this knowing in my heart that it was going to be mediocre and vaguely charming at best, but I wasn't expecting it to be (in my opinion) genuinely detrimental to the series as a whole and truly the worst output we've seen from Rick Riordan in years.
Characters read like cardboard cut-outs who talk in permanent thera-speak, perfectly suited to diffuse every emotionally tense situation with some boring platitude about empathy or boundaries. Mental health is a huge component of this story, but it's so surface-level. What's the point of exploring negative emotions like loneliness, sadness, grief, anger, and jealousy if our characters don't get to actually experience them in meaningful ways? Characters in the original series are flawed; even the heroes are inconsiderate, unkind, or quick to judge, and that's a good thing! It makes for an interesting story. Nobody in this novel gets to act like that with any degree of nuance afforded to them, not Nico or Will or Dionysus, and certainly not the monsters who have spent hundreds of years murdering children (who are good now, we promise). Every complicated issue that could be explored is effectively flattened, and characters are intentionally de-fanged to make the hamfisted way they're shoved into the narrative make any sort of sense. See, it's okay that the Minotaur carried around beads from the necklaces of dead Camp Half-blood children during the Battle of Manhattan as spoils of war, because he knits now! Mr. D is suddenly really interested in therapy and breathing exercises, and we promise it's because he actually cares about the demigods at camp, and not just because Riordan realized that Nico has no one to confide in other than his boyfriend!
And Nico. Poor, fan-favorite Nico. He's almost unrecognizable. Any personality he has is stripped away, and it makes him almost as boring as Will, who is there to act as nothing more than a shoulder for Nico to lean on in the brief moments where he's allowed to express actual feelings. He possesses zero interiority or flaws and attributes that make him interesting enough to be the secondary lead of an entire series.
I could go on. The book was overly long, the pacing was a mess, and it was sentimental in an empty, saccharine type of way. The monster (sorry, mythic!) characters are one-note, and the central thesis that every living being has the capacity to change rings incredibly hollow when, again, we're talking about millennia-old monsters who have somehow never questioned their orders to kill and maim demigods before Nico and Will stumbled into Tartarus. Gods help Percy when he visits Camp Jupiter on break from school, only to find out the creature responsible for kidnapping his mother and trying to murder him in one of the scariest moments of his entire life is now a beloved hero figure amongst his friends and family. This book is great and makes complete sense.
(Why two stars instead of one???? I liked the Cocoa Puffs, and I want 100000000000. The concept of negative emotions being externalized like that is actually really interesting. Those are the only flowers I'll give.)