The author briefly notes that "Paulie, Helen, and the others also managed to find their happiness in due course".
It looks like the minor characters were denied their happy ending, but the author notes that not everything's as happy as it would first appear for the main characters: Bianca begins having an affair with Paulie behind Ace's back, and Ace is furious when he finds out. Carol becomes isolated and lonely, and is unaware that her mother, Massive Numbered Siblings, and a few cousins are all separately plotting against her for the throne. Dirk's men don't respect him because they preferred the old captain and view him as an interloper.
The book's last chapter addresses the minor characters' endings: Paulie finds love, Carol's family no longer cares that she is the Queen, and the old captain is brought Back from the Dead.
The minor characters' happy endings are addressed in a sequel.
The side characters (except Paulie, who ends up alone yet again) are killed as part of a Sequel Hook.
A sequel addresses the main characters' happy endings, but no one else's.
Lampshaded: "What happened with Carol?" "Forget about her, Bianca. Just be thankful everything worked out for us."
Invoked: The main characters decide that they want revenge on everyone else, in a case of Evil Versus Evil.
Exploited: Dirk is a minor character at first, but becomes more involved in the plot in the hope of earning a happy ending.
Defied: The main characters, upon getting their happy endings, tie up loose ends and make a sincere effort to ensure the happiness and comfort of everyone they care about, even those who don't deserve it. Bianca devotes herself to helping Paulie find love, Carol makes her family a part of her running the kingdom (or gives Helen the crown against their father's wishes), and Dirk never forgets the sacrifice of the man who came before him and wins the respect of his men by following his predecessor's example.
Discussed: "Please come with us, Ed." "Sorry, pal. Minor characters finish last, and I don't want to take that risk." "What risk? Even if you don't get a happy ending, you'll be no worse off than you are now."
Conversed: "This is a great book, but it doesn't say what happened to Paulie." "Who was Paulie again?"
Implied: The lead characters' happy endings are thoroughly explained in the final chapter, while the minor characters' endings are not even mentioned.
Plotted A Good Waste: The original plan was to have every non-evil character win out. However, the author deliberately leaves out the side characters to make the ending bittersweet; the more the audience thought about it, the more they would realize how the "happy" ending wasn't all that happy.
Deconstructed: A reader writes a Fix Fic which leaves Ace single and pairs Bianca with Paulie.
Reconstructed: In a sequel, Ace and Bianca break up to accommodate the Fan-Preferred Couple. However, the other side characters and the new characters still get a Downer Ending.
Played For Drama: The selfish heroes knew from the start that others would suffer and/or die for their personal happiness; they just didn't care. At the end, Bianca says, "I can't believe everything worked out for everyone we cared about," to which Ace replies, "That's right, baby. Everything worked out for you and I. And it's not like we care about anyone else."