Interestingly, I was re-reading the chapter so far, and the Nightmare Knight specifically says that once Trebleopolis is destroyed, he'll go after the Ripple Kingdom. Although it could have been just a bluff to threaten Nautilus, it's still making me wonder what the heck this guy's motivations are?

- He doesn't want the legendary hero killed; he could have done that himself.
- He doesn't want the kingdoms destroyed, as he (presumably) just shielded one of them from destruction.
- Somehow having his minions capture princesses is part of his overall goal.
- If he really wanted to rule the world, then why, with all of his seemingly unlimited power, is he just kind of biding his time?