The woman in the Game Over screen of the Sisters mode is Gwendolyn, Eric Lecarde's fiancé from the backstory of Castlevania: Bloodlines.
The Forgotten One is sealed away in the center of the Burnt Paradise.
- Brauner resurrected Dullahan, Legion, the Werewolf, the Mummy Man, Medusa, and The Creature from the memory and history of the castle. He began to resurrect the Forgotten One as well, but found that its power was too strong to control, even with his portraits. Since he could not control it to do his bidding, he painted the Burnt Paradise around it, leaving it with no way out, and no way in to where it was. He instead placed Medusa to guard the Studio Painting in the Forgotten One's stead.
It's not that Charlotte's straight that makes it so "Temptation" doesn't have any effect on her, it's just that Astarte's not her type.
The English script (and thus seemingly every other translation) completely rewrote Charlotte's dialogue following that boss battle you can only end properly using Sanctuary. Where in English she responds to a certain character's thanks for doing so with a cocky "well of course we pulled it off" sort of reply, in the Japanese version she's flustered enough that there's a stammer written into the dialogue - which happens nowhere else in the entire script! It might just be that she's got a thing for tall handsome people who can use swords... and have pretty blue eyes...and deep/husky voices... and Astarte, for all that her "personality" is pert and flawless, just ain't that kind.