Flandre is the younger sister of Remilia Scarlet
, who has been locked up in the basement of the Scarlet Devil Mansion
for her entire life (495 years). The reason for this is due to her unstable personality and incredible destructive power, although she still has great respect for Remilia despite being locked up. She has little knowledge of the outside world, and it isn't until the heroine turns up during the Extra Stage of The Embodiment of Scarlet Devil
that she has contact with a human other than Sakuya.
She has scarlet eyes and blonde hair, and she wears a red dress and vest with a pink blouse underneath, as well as a pink hat with a red ribbon attached to it. She carries around a wand which is apparently the mythical Laevatein. Her wings seem to be made of iron and prism shards.
- A silhouette of Flandre is featured on the cover of The Embodiment of Scarlet Devil.
- Flandre's second Spell Card, "Taboo Laevatein", has the same name as the sword/wand of Loki, a Norse God known for causing mischief. During Ragnarok (the Norse equivalent of the Apocalypse), the fire giant Surt uses this sword/wand to burn the entire world, with the exception of one safe haven. It is rather fitting that she wields such a destructive weapon, as it fits with her destructive powers.
- Flandre was born in 1508 A.D, according the timeline of Gensokyo. This makes her the only character whose date of birth is revealed.
- It is speculated that Flandre's wings are artificial, as they do not resemble typical bat wings, or any organic matter. It is believed that she made them herself and then attached them to her body, suggesting that she either lost her original wings, or she wasn't born with them. Some fans believe the crystals are used to store magical energy, which increases her power.
- Some fans have depicted Flandre as being fond of Marisa Kirisame, due to the last part of the conversation they have in Marisa's Extra Stage in The Embodiment of Scarlet Devil.