Petra Leyte hails from Arlam Village near Roswaal Manor. She first explored the manor during childhood visits, invited by Natsuki Subaru to play games like tag with other village children. This familiarity with the mansion's layout later motivated her to apply for a maid position. At around twelve years old, she answered a recruitment notice seeking to assist Frederica Baumann. During her application, Petra highlighted her practical sewing skills and recent cooking abilities, learned within a month and a half, alongside her knowledge of the manor's interior from previous play. Despite Frederica's initial concerns about her age and the need for immediate help, Petra's determination and demonstrated capabilities secured her the role as an apprentice maid. As part of the Emilia Camp, Petra performed standard maid duties while building bonds with camp members. She shared a particularly lively dynamic with Subaru, often teasing and challenging him. Her responsibilities grew during critical events, including staying at the manor during the Sanctuary incident and later joining the expedition to the Pleiades Watchtower. She aided in logistical tasks during the camp's journey into the Vollachian Empire to retrieve Subaru and Rem after their teleportation. Petra underwent noticeable physical and emotional growth. She grew taller and developed a more graceful demeanor, achieved through dedicated self-improvement like daily mirror practice. Her rising confidence and responsibility became evident when she took on the role of dragon carriage driver, skillfully handling the reins of Subaru's ground dragon, Patrasche. During one such journey alongside Meili Portroute, Petra maintained focus on driving while sharing lighthearted banter, demonstrating seriousness in her duties and care for her companions. She recognized Meili's efforts to ease tension during travel, showing awareness of group dynamics. Petra also asserted herself to correct unsafe or disruptive behavior during these missions. Her camp relationships evolved significantly. She formed a close, teasing friendship with Meili, evident during their shared carriage journey through mutual jokes and expressions of thanks. She maintained her bond with Patrasche, earning the ground dragon's cooperation through firm yet respectful guidance. Petra's loyalty to the Emilia Camp remained steadfast, participating in key missions like the infiltration into Vollachia. She later utilized an oath-bound curse mark to broker a meeting between Emilia and the mole people's representative, Musica.