(Scarlet Devil)
Mistress of the Scarlet Devil Mansion
Born in the 1500s to a poor family in Romania, Remilia Scarlet and her sister Flandre Scarlet were the victims of a vampire attack which left both herself and her sister changed...both of them were cursed with vampirism from their attack.
Fast forward hundreds of years later, and Remilia Scarlet is a renowned and feared name, also referred to as the Scarlet Devil, ruling over the Scarlet Devil Mansion. She has employed many fairy maids under her employ - of which they are under the guidance of the Head Maid Sakuya Izayoi. Remilia's gatekeeper Hong Meiling guards the entrance to her mansion, and Patchouli Knowledge alongside her familiar Koakuma are the guardians and keepers of the library. Finally, her sister...her dear, beloved sister Flandre Scarlet, is locked in the basement for her own good, her unnaturally strong powers being deemed too dangerous to let her roam free. Flandre has taken...surprisingly well to this confinement, being more comfortable staying at home in her own safe space rather than venturing out...sometimes, however, Flandre gets the desire to explore some before returning home.
Remilia Scarlet was behind the initial incident known now as the Grand Gate Incident, leading to Gensokyo being open not only to the outside world...but to many worlds. First and foremost among them however was Terra. Her mansion is easily accessible from Aslund if one ventures to the Cursed Wood. From there one can venture into the mansions' grounds. Once inside the mansion, an individual can either leave and end up back within the Cursed Wood, or they can leave and end up in Gensokyo itself...this pseudo-border was not created by Remilia, however she certainly took advantage of it once it was discovered the Scarlet Devil Mansion was existing in two areas simultaneously, allowing for...interesting residents to attend parties she would throw, frequently inviting those who she met on Terra to visit.
The Scarlet Devil Mansion maintains a policy of armed neutrality with many factions, willing to do business and trade with others so long as they retain this neutral stance. Their only non-Gensokyan alliance is with the Vankoryth Détente, an alliance of fellow vampires who Remilia has agreed to cooperate with, if only because it means more of her own kin to ally with.
Remilia Scarlet is an especially powerful vampire, being skilled in more traditional magic alongside Gensokyo's own spell card and danmaku duels. Outside of Gensokyo she is allowed to shrug off the artificial shackles imposed by the Hakurei Miko, and exercise her true power...
Spear de Gungnir
A spear made entirely of energy Remilia is able to summon, she is adept at combat with it, however she often throws the spear of energy. It is incredibly accurate due to how fast it travels after leaving her hand.
Fangs & Claws
Being a vampire, Remilia is able to utilize her fangs and claws in battle, however she often chooses not to as this not only ends up dirtying her clothes with other people's blood, but also because it is an "unrefined, animalistic" form of combat she sees as beneath her.
Control Over Fate
An esoteric and not well understood ability, even by Remilia herself, she is noted to have the ability to "manipulate fate", steering things subtly in a direction which is favorable towards her. This can be interpreted many ways, and Remilia does not confirm nor deny whichever may be the correct interpretation. The first interpretation is she is directly controlling fate akin to the Norns of Norse myth - having limited access to herself and those closest to her. The second interpretation is that she's capable of steering things in a favorable way for her, but the method of doing so is subconscious and Remilia is wholly unaware when she does this. The third and final interpretation is that she can directly control fate as per the first interpretation, except she is only capable of manipulating that which she is already consciously aware of. Thus, unlike the first interpretation, if someone is hiding something from her...she can't manipulate fate in order to alter the outcome of what is being hidden.
Whatever the case may be, Remilia prefers her secrecy and wants to keep people guessing. It's more fun that way.