(Part 1)
Alright, so now that I've thought about this for two months straight and read the original novel of Phantom of the Opera, there has been some shuffling of roles.
Specifically, I was wrong about Raoul being Fathom. That role is much better filled by Clearsight's school friend Listener. (Still not romantic, though.) *
FATHOM, displaced from the role of Vicomte and probably not ever right for it in the first place, now shares with Indigo the role of the Persian, book Erik's old friend who gets cut from nearly every adaptation of PotO despite being the coolest character in the book.
Meanwhile, we also have here the character who was easiest to cast--Carlotta and Allknowing are just straight up the same character: the skilled, respected professional who resents being replaced by the antivillain's young, talented crush.
Also featured are Silverclaws (based on La Sorelli from PotO-the-book, who has no equivalent in either the musical or WoF) and Daddy Daaé (who just doesn't get a name, I guess, because neither Tui Sutherland nor Gaston Leroux thought he needed one).
*Brown-tabby-stripes Listener comes from user Oleandy on DeviantArt, who I'm not going to link to because Mom doesn't want my little siblings (who follow this blog) running around on DeviantArt.