/jp/ - Otaku Culture

All I ever knew in as canon in regards to Flandre is that she's a 495 year old vampire kept inside the Scarlet Devil Mansion due to her bouts of insanity. Remilia, Patchouli, Sakuya, and the protagonists of Mist of Scarlet Devil are the only ones who know of her existence to the full extent, though I think it fair to assume that Yukarin does also. It is said she knows absolutely nothing about the outside, yet has expressed interest in finding out. I also believe that at one point Patchouli called a rainstorm to occur which successfully diverted Flandre from leaving the mansion. Although she has the express weakness of vampires, I do believe she can touch holy symbols without pain.

Pretty much all I know about her. Touhou is perhaps not the most elaborate when it comes to explaining characters, but it thankfully gives you a good template so that fans can develop upon them as they see fit.