Claudia Hortensia

Claudia Hortensia is the deceased wife of Kirei Kotomine and mother of Caren Hortensia.

Claudia was a terminally ill woman with only a few years left to live. Kirei Kotomine met her while trying to overcome his innate evil nature, believing that being with a woman would be his last attempt to find normalcy. He wished for the ordinary happiness of love and a family despite having no interest in it, ultimately picking a woman with no future. She came to love him, eventually bearing a child, Caren Hortensia. Kirei tried to love her, but felt happiness at her and Caren's suffering and despair. Claudia, knowing of his mentality, tried to save him, but that only made him want to see her grieve all the more. He understood that she truly meant to save him, and despaired that not even she could fill the void within him.

(Source: Type-Moon Wiki)