Beryl served as an assistant to Gelimer while he was experimenting on his ultimate weapon, Xenon, in secret. After Gelimer has Xenon defeat a clone of Von Leon, the Resistance breaks into the secret lab. Gelimer decides to use Xenon as a weapon against the Resistance, and traps Claudine. When Xenon is about to capture the rest of the Resistance, he starts having faint memories of his childhood, temporarily incapacitating him while the rest of the Resistance escapes, with Gelimer and Beryl in pursuit.
While Gelimer and Beryl are out, Roo-D, a robotic rabbit who also served as Gelimer's assistant, reveals that Claudine is the key to Xenon remembering his past, and encourages him to escape with her. However, Gelimer and Beryl return before they can exit, and Beryl attacks Xenon, but is defeated. Gelimer attempts to regain control of Xenon, but Xenon's desire to regain his memories allows him to bypass Gelimer's control. The Resistance leaders then show up and escape with Xenon and Roo-D, leaving Beryl behind.
While Xenon is getting adjusted to living in Edelstein again, Beryl tracks him down in Edelstein's Park, revealing that she followed him through his pulse, and vows to return for him on Gelimer's orders. Xenon leaves Edelstein to protect the Resistance, and ends up in Henesys. After sensing Beryl's pulse, he escapes through the Interdimensional Portal to Pantheon, and helps the Nova repel Magnus's forces. Beryl eventually catches up to him in Pantheon, and Xenon defeats her once again; he soon gets the feeling that Beryl hates him.
After Xenon blocks his own pulse with the help of the researchers in Veritas, he is soon sent to Magatia for a mission, where he encounters and defeats Beryl once more. Beryl is enraged at her loss, lamenting over it, and reveals that she does indeed despise Xenon out of jealousy, as Gelimer still views Xenon as highly important compared to her, despite his betrayal. Xenon says that her emotions are making her human, which she shows disgust toward right before escaping.
Xenon encounters Beryl once more, where she tells challenges him to one last battle in the secret laboratory, which is now abandoned. After Beryl loses once more, she states that, contrary to her prior belief, Xenon's memories and emotions made him stronger than her, and admits defeat. She labels herself as a defective unit and expects to be dismantled in the near future due to her failure to beat Xenon. Xenon tries to convince her to come with him to Veritas, but she states that she cannot betray "father" (Gelimer), and leaves. Xenon returns to Roo-D for advice, and Roo-D promises to help Xenon find Beryl for her own safety.
Beryl is encountered in Act 4 of Black Heaven disguised as an android named Bitterbot. She was found by the android couple One-Eye and Three-Hands and was taken in as their adopted daughter. When encountered by the member of the alliance, she is far more pessimistic than her adoptive parents, telling the alliance member that their efforts will be fruitless, believing the Black Wings unbeatable, but nonetheless aids the member in covertly boarding the craft.