Race: Vampire
Ability: Destructive Power
Age: More than 495 years
Occupation: none
Location: Scarlet Devil Mansion
Flandre is the younger sister of Remilia and the "dirty little secret" of Scarlet Devil Mansion. Because of her unstable personality and incredible destructive power, her sister has had her locked up in the basement for nearly 500 years. She knows little about the world outside and until the heroines arrived during the Extra Stage of Embodiment of Scarlet Devil.
Flandre's Second Spell Card (Taboo "Lävatein" or Lævateinn) shares its name with the sword (wand in some versions) of Loki, a Norse god known for causing mischief. This sword/wand is used by the fire giant Surt in Ragnarok (the Norse equivalent of the Apocalypse) to burn down the whole world, except for one safe haven. Fitting that Flandre would be wielding a tool of such destructive might.
Her boss theme ("U.N. Owen was her?") and her second-to-last spell card ("Secret Barrage - And Then There Will Be None?") are references to Agatha Christie's novel And Then There Were None (also published as Ten Little Indians and Ten Little Niggers). U.N. Owen (which the characters of the novel naturally deduced to mean "Unknown" and also recognized as referring to Mr. Owen's wife) was actually seen in person in that thriller but was only revealed at the end.
Ability: Destruction of anything and everything
The Extra Boss. Also the Mistress's younger sister.
She is a vampiric magical girl and has been the Scarlet Devil's younger sister for about 495 years.
She's kind of nuts and isn't usually allowed out of the cellar, but she usually doesn't try to let herself out.
She really respects her older sister Remilia, but her raw destructive power far exceeds that of her sister's. Although she is usually docile, her insanity makes it difficult for others to understand her.
When vampires attack humans, they generally try to take their prey alive so that they can suck its blood afterward, but Flandre has always been fed with cooked dishes, so she doesn't know how to properly attack a human. Whenever she tries to attack a human, she can't control herself and blows them away without leaving a spot of blood.
Perhaps she can't tell that her daily meals are made from living humans.
Her meals look like such harmless foodstuffs as cake and tea, after all...