Laeticia

The French girl who Ruler chose as her possession vessel. She's a decent and honest person who has no Magic Circuits, but her religious piety alone surpasses that of others. Though she has lived an extremely normal life, she loaned her body upon Jeanne d'Arc's request. Her facial features and style is only partly similar to Ruler's. Due the effects of the possession, her body was somewhat changed to match Ruler's. After Ruler left her body, she returned to normal.
She served as the witness to Ruler and Sieg's relationship, and she was, in a certain sense, the final stronghold for Jeanne, a sheep that allowed Jeanne not to notice her own feelings of love.
She is an ordinary person who got dragged into the Great Holy Grail War, but emotionally it was like watching a movie inside a dream for her, and after it ended her memories of it wore away in the blink of an eye. Even so, she doesn't make vague prayers anymore, as she found a direction for her prayers in the form of wishing that “those two may find happiness together,” and she prays believing in such small miracles every day.

Fate/Apocrypha material: Fate/Apocrypha Encylopedia