Chiba Nagisa

Chiba Nagisa is the only female member of the Holy Swords of Kyoto. She is arguably one of the most strong willed and tough characters in the entire show. It is hinted she is attracted to Toudou. After Zero leaves during the first Black Rebellion she begins to harbor resentment towards Zero. During the second season she rejoins the Black Knights after being freed By Zero. However she still clearly has trust issues after the first rebellion.

Spoiler

After learning about Lelouch and Geass she takes part in the betrayal against him and fight against Lelouch when he takes power.