Species: Vampire
Age: Approximately 500 years old
Abilities: destroying absolutely anything and everything
Location: Scarlet Devil Mansion basement

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 ordered her not to leave the mansion for nearly 500 years. 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 in order to suck its blood afterward, but Flandre has always been fed with cooked dishes, and thus doesn't know how to properly attack a human. Whenever she tries to attack a human, she loses control of herself and blows them away without leaving a spot of blood. Her apparent age is about the same as Remilia Scarlet (who looks to be around 10, even though Remilia is 5 years older and they're both about 500 years old). Flandre can destroy anything she wants by moving the "eye" of the object, where the tension is highest, into her hand and pouring her power into it. When she clenches her fist whatever she has moved the "eye" of into her hand will be destroyed.

She also has extreme physical strength. Unsurprisingly, all the toys she plays with get broken. Flandre's wings have an unusual appearance which bear almost no resemblance to a vampire's typical bat-like wings (or even organic matter). It has been speculated that her wings are artificial and that she fashioned them herself and then attached them to her body. She may have lost her original wings or been born without them.