The Sisters of Battle.
A myth to some, a threat to others.
The Church maintains several standing armies, the fabled Church Knights who answer to no king or lord, but instead to a higher power, the Ordo Militaris or the foot soldiers of the Church, and the Ordo Inquisitorum, the Church's terrifying secret police. Many of these organizations are cloaked in legend. Everyone has heard of the deeds of the Nalladorn Chapter, or the fabled Whitehelm orders. Yet one order stands out from all the rest, veiled in mystery and ceremony. They keep themselves aloof from the cities and churches that they are sworn to protect, roaming the land in search of witch hunters, heresy or wrongdoing, which is then purged with utmost zeal, wherever it may lie. Whilst the other orders of the Church have learnt discretion, and to a greater or lesser extent have let their beliefs become mingled with the beliefs of the people that surround them, this order keeps itself apart.
The Sisters of Battle are an organization veiled in myth and legend, everyone has a story about the Sisters even if they've never seen one. They are an enemy of bandits and demons alike, though their hard-line stance on various matters has made them few friends among the nobles who own the lands over which the Sisters ride, though few are stupid enough to directly challenge the Sisters, who are known to be competent swordswomen, in fact that is perhaps the only thing that the legends and myths agree on.
However all this doesn't matter to your character, a young peasant woman fleeing from her village, either fleeing from raiders or else from an arranged marriage. She runs into the woodland, seeking refuge among the trees, however the raiders have dogs and so they're able to keep track of her easily and so they manage to catch up to her, however before they can take do anything to her, they are suddenly intercepted by a party of knights on horseback wrapped in creamy white robes and silvery white armor. The knights cut the party down, leaving your character alive. The leader of the knights then takes off her helmet to reveal the face of a young woman, in her twenties or so who introduces herself as Sister Vail of Squad Castiana of the Sisters of Battle. She takes your character back to her chapel, and invites your character to stay for a week or so in the company of squad Castiana, and your character finds herself contemplating joining the Sisters, and taking a peculiar interest in the leader of Squad Castiana.
However things are moving in the darkness, and overseas, a war is brewing, one which the Church could be getting embroiled into, and if that's the case then the Sisters of Battle will be on the front line.
If you're interested, post here or PM me.