Mason: He could still have grown up with them, and like you said, maybe have gone somewhere for his education or gotten a job on the side? Not sure. He doesn't have to be involved at all too. I just picked whatever characters I had ideas in mind for, so that definitely doesn't mean we have to go with them.
Katja and Emma: Well, I figured Cordy would get into the library before Katja and Emma to begin with. But I doubt she would be very quite. She'd probably be freaked out and thinking out loud. What with having just been discovered by Jack. So perhaps they hear the ruckus and track her up to the library. By then I assume she'd have already found the book and realized its importance. She could sneak away, but eventually be noticed and have to run and hide the book. Then Drake could stall the two, who as you stated, would make it so he wouldn't be seeing Cordy for a while. Just because Drake may have been on the same fleet as them, doesn't mean they have to get along. Perhaps they take him back to the steampunk city? Not saying he wouldn't get away at some point though. ;D
But this way, maybe when Jack comes to find Cordy at the island she could be distressed about Drake, and ask Jack to take her with him so that she could go try and find Drake.
Leticia and Filipe: I like the sound of that. Maybe the book could have been written by Leticia? If it was, it could have clues to her whereabouts. And I dunno, maybe Cordy's super magical mermaid tracking instincts will kick in. xD
But I definitely like the idea of the necklace originating from their utopia. I could see it having been made by Leticia or her ancestors to allow a forbidden love a chance to happen. Or for the same reason, have it be an heirloom past down through Filipe's family line.
Gerard: Yes to Vergesburg being evil. Dun dun dunnnn. So that can be where all the fish DNA happenings are. Where Drake's old fleet, and Katja and Emma's fleet are from. Along with Gerard's fleet. And I like the idea of maybe Gerard's fleet leading the charge to find the necklace - perhaps he also just enjoys getting into fights with other fleets - while Katja and Emma kind of do their own thing. They'd still be looking for the necklace, but on their own terms.
Perhaps in the right hands - this book might have details on this as well - the necklace could change the Earth. If used by the merfolk perhaps it could entirely flood the world, and in the hands of a human, restore the old world.
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Post should be up shortly.
I do think I'll have them fall through in my post.
And alrighty, I should be heading to bed soon as well. But tonight was amazing!