Mordred is a Servant who won the previous Holy Grail and made a wish to become a human with her powers as a Servant still intact.

Oh hey Master I been waiting for you happy face says hello, Mordred's outfit is that she wears a black long-sleeved shirt with a cross-shaped necklace and she wears blue jeans and looks Mordred a little mature and still like the tomboyish girl and Childish she used to be when she was a Servant