Some theories about Sakuya's origin conects her past with the Lunarians (By Hieda no Akyuu in Perfect Memento in Strict Sense). So, you can play a lot with those lines and theories.
regarding the plot, I'm going to say Flan is out of the fight because she's never had to endure actual damage, Remi, on the other hand, is going to get knifed and she won't even flinch and *then* will slap pre-sakuya here into utmost servitude.
Ha! ... What?But she still didn't havemore than the most basic killing intent.When she saw the figure,Toying with her, and mocking her, her intention is to try to tear her to pieces while playing around.And then as she thought that, she was blown away.was a girl from whom everything superfluous had been stripped away.the image that played through her mindWhat witch has she ever encountered who rivals this beautiful witch and her followers?