The au goes something like this:
Comte and the residents live in the mansion just outside the town where Belle lives, similar to how they live just outside of Paris.
They are all from their parallel countries, so the French boys are from Rhodolite during different time periods, Shakespeare is from Jade, Sebastian is from Ruby and so on.
Comte is just some Rhodolitian noble that is really wealthy and mysterious, just like in Ikevamp. Everyone is still time traveling vampires and all that.
Belle is still Rhodolitian, she just managed to go through the door and somehow found herself like. A year in the future.
Anyway she makes friends with everyone and ends up taking care of their library in exchange for room and board in the mansion.
She still works at the bookstore with Akatsuki and finds Rio on the road and all that. Except at the end of the day she goes home to a mansion full of vampires and helps clean and organize the library (Put your fucking books away Leonardo! The floor is not a bookshelf!!)
Comte is absolutely ecstatic he has a girl in the mansion that he can give dresses to and take to balls with him every once in a while.
Due to this, many of the Rhodolitian nobles thought Belle was some mysterious, reclusive noblewoman from afar before Comte was just like "nah she's my daughter lol"
Rio, of course, was adopted by Comte the moment she brought him home.
He still goes through jobs like crazy in town. If Akatsuki won't hire him, maybe he could help Sebastian at the mansion?
(Sebas is feeling threatened )
Anyway, he lives in the same mansion as Belle, so that's enough for him.
When Sariel first spotted Belle, she was beating the shit out of someone who was being mean to one of the kids Isaac and Napoleon teach.
Napo was just standing there watching. Isaac was also watching but he was debating whether to pull her off or not.
Things got a little complicated when Sariel took her to the palace.
It was easy to nab her from the bookstore, but then he had to deal with a whole family of angry vampires.
(Of course he didn't know that last part, but there were many very strong men showing up at the castle within an hour looking for Belle.)
Whether or not Belle was a commoner was called into question, since she lived in a nobles household.
Eventually, it was decided that since she was technically staff there she was still a commoner and qualified to be Belle.
Jin and Nokto don't dare flirt with her after seeing her very angry family out front.
Wait, how did Rio get here? He's Belle's new attendant?
Sebastian suddenly shivers back at the mansion. He can feel his position in danger.
Now for Belle's cover story. She will be the daughter of Viscont x and...
Le Comte has been introducing her as his adopted daughter at social gatherings??
The adopted daughter of Le Comte de Saint Germain studying at the palace was a pretty good cover story, even if some nobles didn't approve of her "adopted" status very much.
This comes in especially handy when the foreign princes come to visit.
Everything is technically true! (Comte is currently halfway through the legal adoption process)
When Gilbert drags Belle into the ball most of the nobles are like "oh hi :) where's your father?"
Especially since Le Comte is AT THE BALL and he comes over to give her a hug and catch up.
I haven't seen you in two weeks ma cherie, I brought you a diamond bracelet.
Silvio tries to confront her but daddy Comte is not. Having it.
"Hello Prince Silvio :) I see you're talking with my daughter :) what business could you possibly have with her :)"
(Rio still throws wine on him later just for being a dick)
Thankfully, Comte's constant extravagant gifts have prepared her well for Silvio testing her.
You wanna give her a dress and enough jewelry for three people? Thanks, that's so sweet :)
She has been to fancy dinners with Le Comte, so she knows proper table manners and how to handle her silverware. She also knows how to dance well due to going to balls with him.
Silvio and Gilbert are at their wits end trying to expose her.
They can't even accuse her of being a commoner bc she can just. Take them to her house and let them talk to her dad.
Theo is an art dealer, but there isn't as much restriction on art in this au.
All art is celebrated in Rhodolite, so most of his job consists of helping newbie artists getting into galleries and exhibitions.
He also spends a lot of time yelling at artists who undercharge for their art and people who try to haggle artists down for their works.
Gil sees a painting Vincent did of Belle putting books away in the library while Leo is sleeping on the floor and thinks he's got her.
"Teehee, why would the daughter of a nobleman be putting books away in his library?"
Theo: "that's how libraries work you dumb fuck. You put your books away when you're done with them."
Keith doesn't really care about her. She's really nice and joins his teaparties with Licht and Yves sometimes, but she's really not very suspicious.
Alt Keith would love to tease her a bit... but he's seen her talking to some of her "brothers" in town. It's rare to see people that look like they could rip him limb from limb, and he would rather not cause any trouble with Belle's extensive family.
Rio and Arthur actually get along pretty well, they both play-flirt with Belle but Arthur is never serious. Rio is half-serious but keeps it toned down.
Mozart is reclusive as usual but it's obvious he's a former Obsidianite due to his name and accent. He would rather not deal with people being weird about where he comes from.
(He and Yves would probably bond over it if they ever met)
After the selection process is complete Belle goes back to her normal life and the foreign princes leave since they couldn't find anything on her.
The next time she goes to a social event with Comte everyone asks how her studies in the palace are going.
"Oh I dropped out. It wasn't as interesting as I thought it'd be." :)
The other nobles are a little flabbergasted but they don't dare say anything about it.
Comte is very sad that Silvio gave her so many gifts and starts going on a spending spree to make up for it.
HE is the one who buys you a new wardrobe every season, not that asshole >:(
Anyway that's all I got, feel free to expand on it or use the au or whatever :)