Touhou Headcanons!

Sakuya's backstory

My own version. Any sort of speculations are welcome.

Sakuya is the daughter of Jack the Ripper, a serial killer from London, England. Her mother died when she was giving birth.
Sakuya then discovered her father's occupation, which is a vampire hunter. It sparked Sakuya's interest and wishes to become like him one day. Knowing his daughter's dream, he gladly taught her everything he knew, which is knife techniques he uses on his daily basis of hunting.
He told her that the most effective way to kill vampires are by silver knives and so gave her three special knives in her possession : red, green, and blue handled silver knives.
Years after years she finally became a vampire hunter, a rookie one. Jack was proud of her and to improve her skills, he gave her missions all around the world. To that point she was a well-known vampire hunter.
One day, during a mission, Sakuya waited and waited for her father's return as she eat her dinner. Then, it struck her. She finally became worried and decided to head out to her father's mission location, the mansion from France (headcanon from Merc).
After she arrived she discovered the corpse of her father outside of the mansion building. She felt devastated and full of bloodlust, seeking for revenge. She entered the mansion and seek for the one who killed her father. She yelled, screamed on the top of her lungs, to identify this vampire who bested her father. Then, a vampire that is young looking, appeared before her, still covered in blood. That young mistress admitted her crime and Sakuya began to battle against her.
The battle ends, the two are wounded, and Sakuya heavily injured, nearly to die. Sakuya murmurs, “I'm sorry...” to herself but Remilia overheards. In this dark mansion, raining heavily outside, Remilia, for the first time, felt pity towards a fellow young human. She then decides to make a deal with her. She'll change her fate in exchange she'll serve her as a punishment for attempted hunting. Remilia introduced herself and changed her name into ‘Sakuya Izayoi’. Sakuya only nods once, and soon she closed her eyes.
She woke up in a bedroom with Remilia waiting beside her, time magic in her possession. She couldn't remember anything and only smiled at Remilia, gently patting her head. Only Remilia knows what happened, and for 100 years, Sakuya, full of loyalty, served her mistress as the Chief Maid of the Scarlet Devil Mansion.