Aren't there quite a few energies out there that actually are invisible? >.>

And I'd definitely appreciate a notable NPCs list. Especially with one or two sentence bios, to give a quick idea what they do and how they might interact with the PCs. 

Actually, I had a thought concerning Lucas making himself useful, and I don't know how much Serena actually needs the help, but he might stick around her just in case. That, or just doing whatever anyone tells him to, really.