I'm very on board for Art getting involved with Bucky and Elsa! We've talked a little already about Anne-Elsa interactions, but do you think, being the mayor, Elsa would be aware of Anne's more quiet visits in town (even if obviously in the dark about why)? Just... okay, quietly accepting for years that this is something the queen does, no big deal.
Similarly, potential for Yona and Elsa interactions? Yona asking for help at the mayor's office? Then again, maybe she wouldn't if she's recognisable as a pureblood and knows it's not a vampire-friendly town. I could also offer Sebastian to ~save her~ from hunters? "Oh, think nothing of it, of course I'd help, no need to repay me... ACTUALLY, how would you feel about turning this little kid for me pfft it's not quite as painful as it looks?"