Shirley has a major role in the middle of the first season. After the Black Knights, led by Lelouch's alter ego Zero, indirectly cause the death of her father during the Battle of Narita, Villetta Nu suggests that Lelouch may be involved with the Black Knights. The distressed Shirley follows him and discovers that he is in fact Zero, but shoots Villetta to protect his secret. She tries to write a letter about her feelings on the situation to Lelouch, only to throw it aside. Mao then uses his mind-reading Geass to manipulate her into killing Lelouch for him, but she cannot bring herself to do so. To alleviate her suffering, Lelouch uses his Geass to erase Shirley's memories of him. Lelouch expresses regret for having to do so. Shirley rediscovers her letter near the end of the first season, but cannot confront Lelouch about it because of the rebellion that takes place.
In the second season, Shirley's memories, along with the rest of Ashford's Student Council, have been rewritten by the Emperor, erasing her memories of Zero's identity for the second time. Her affection for Lelouch has returned over the intermediate year. Her memories are restored by Jeremiah Gottwald's Geass Canceller. After coming to terms with it, she comes to understand Lelouch's motivations and forgives him after realizing that he is alone in his quest. She resolves to support him as the one true thing in his life, but before she can find him, she runs into Rolo. She attempts to reason with Rolo so he can help her join Lelouch, but when Shirley mentions that she wants to help Lelouch reunite with Nunnally, Rolo snaps and mortally wounds her. She confesses her feelings to Lelouch when he finds her and dies in his arms despite Lelouch's desperate attempts to command her to live. Her death is ruled as a suicide. Lelouch then blames the power of the Geass in causing her death and orders the destruction of the Geass Order.
