>>2Yeah. She's just in FGO. Not other Fate works. It's probably not too bad to play through the game anymore. Though she's really only in a few chapters of the main storyline. She had a couple events and shows up in others.
She was intially a villian in the France chapter. Created by a HGW wish to be an idealized revenge seeking Jeanne d'Arc after the real Jeanne was burned at the stake. She starts destroying France with an army of wyverns, fire and corrupted Servants she summoned. This was in the early part of the story and she didn't count as a Heroic Spirit.
Later she got her own event by popular demand and became a Heroic Spirit but an anti-hero in the Avenger class. Then she got a Summer event where you help her make doujins and can get her swimsuit freebie version as a Berserker with a bunch of YYH references and THREE katanas.
Later she plays a very prominent role in the Shinjuku 1999 story chapter. Which ends with her demanding a dance.
Recently though, Nasu the creator had a fit about Avengers as a class being edgy. So they all get removed from the story, at least temproraily. He wanted to remove them permanently for good though for some dumb reasons.