Do you know that Rider's true name is Medusa? Same like the greek myth, She has 2 older sisters. They are Euryale and Stheno. They appears in game version of Fate. They are twin and very cruel to Rider
Just check this link:
[link]I don't know wich is Euryale and Stheno...twins...
But I love to see them with Rider. Very cute!!