"After Shirou has Assassin materialize, Saber is angered at her presence, thinking her to be a "foul hag." As they talk about the other strong Servants of the Red Faction, Saber briefly wonders about the possibility of one of them being her father, although Kairi dismisses this. She is annoyed by Shirou requesting her true name to be revealed, but notes that Assassin's laughter bothers her even more and is pleased when her Master refuses. As they leave, she cannot sense any followers, and compares Assassin's treacherousness to that of her mother."
Basically Semiramis is technically as close as you can get to being Morgan Le Fay personality wise without actually being her, at least her Witch Queen aspect which Mordred is only familiar with.
And from Artoria's and Kay's comments about Morgan and her overall personality "Morgan greatly hates her sister and possesses a great obsession for Mordred to take the throne from her. She changed greatly throughout her life from a "fine lady" to a "frightening thing" according to Kay, and he describes it as if she had three women inside of her. Having started with the "innocence of a fairy", she became "as magnificent as a warrior maiden", and "then suddenly possessed the brutality of a witch." Kay believes she may have had similar burdening circumstances as Artoria due to their parentage. Artoria considers Morgan not only her sister, but also like a mother to her and a reflection of herself. Artoria also says Morgan has a more kingly disposition than her, and was more loved by Britain than her"
Additionally Mordred also makes note that basically becoming Ruler of Britain, basically is like sacrificing yourself from ever being happy, to laugh, to cry, etc.