Teen Wolf Mythology
In 1764, Marie was the sister of Sebastien Valet and a skilled hunter who was skeptical of the supernatural's existence. When the beast attacks her village, Marie lead a hunting party to kill it as per her brother's request.
They hunted from dawn to dusk, but, when night falls, The Beast attacks. She was rescued by Henri Argent who explained that the beast was a werewolf and offered to teach her how to combat the supernatural.
Marie-Jeanne poured wine for everyone in the inn and discovers Marcel, while not the Beast, has been covering for the creature by hiding the bodies in the inn's cellar. She was shocked to discover that her own brother is the monster and had no remorse for what he had done.
For three years, Marie hunted Sebastien until the winter of 1767 finally. She picked up the spear that was hidden in the snow. She quickly turned to face Sebastien. Momentum carried the beast onto the spear which protrudes out his back. As Sebastien dies, she promises that no one will remember him, but only as a beast. Marie and the townspeople initiated Damnatio Memoriae to erase every trace of her brother's existence until Marcel found a way to revive him.
Marie and Henri eventually marry and start a family.
Real World History
Marie-Jeanne Valet and her younger sister were reportedly attacked by the beast while crossing a creek near the River Desges. Valet successfully defended herself and her sister with a bayonet mounted at the end of a staff, wounding the Beast, which threw itself into the river and thrashed about madly before escaping.
The Royal Gunbearer praised Valet and compared her to French heroine Joan of Arc.