I went ahead and beat the game with William. Not like there's much of a story, but with the second character, most of the dialog is stripped out. No Elf dialog for the bridge taken out before going into Hells Castle, no dialog in the Elf Village (that is different from C-331 character). As soon as you defeat the end boss, "Game Over" and then credits roll. lol
C-331 stats ended up being 82.2%, Lv 34, 6 hours, 24 minutes.
William stats ended up being 89%, Lv 61, 3 hours, 10 minutes.
Edit: Tried making a new character (last save slot 3) for name, "REDANGEL" but it appears like it didn't trigger the new unlock, soooooo there must be a NPC prompt that I am not finding somewhere in the game world..but then...according to this thread:
https://pyra-handheld.com/boards/threads/4th-character-in-blue-angelo.16610/
You can only do it with the first character C-331. Yikes. Well, I don't think i'm going to bother going back and searching for the 5 star powers with that character (only got 2 out of 5). I guess the game treats the William character as just a play run, with no real consequence on the story or any gameplay unlocks. Shame.