>>49441137
Thanks for the historical context.
It's doubly funny, because the way I have it in my head, the Butler's pledge is invalid on many different accounts. First, he swears to Remilia because he thinks being sent away from the mansion will result in death and he fears dying before being redeemed of whatever landed him on the Road of Reconsideration and going to Hell. Second, even when he learns of the Village and the Hakurei Shrine, he ignores the option, because he's already sworn an oath at this point and thinks it's equivalent to betraying a confidant. Third, his oath is ultimately a lie, since he can't serve two masters(never mind Colossians 3:22-3:23, which is an inspiration for the story, Remilia's a vampire and likely isn't too keen on a servant who believes in God). And finally, like you mentioned, Remilia doesn't really have the ability to take an oath since she has nothing to swear to.

I like the idea of throwing Flandere at such a confused person, she's simple and more 'pure' in a sense. Would be fun to introduce her after four chapters of Downtown Abby: Halloween-edition civility for her to completely upend things. The Bulter's behavior could be conveyed as reasonable decisions in fantastical circumstances up until that point, until Flan asks the obvious, straight-forward questions that expose his dissonance and, ironically, comes to understand him better then anyone else because of that bluntness, which is ultimately how she discovers his secret.
In this sense, I think of Flan as sort of a "dark illuminator". Honest, but her revelations are going to hurt.