In contrast to her husband, Nancy was kind and opposed to war. Double mentions how Nancy used to come to the Grand Cathedral every day to pray for peace while noting Parasoul's anger at her and Valentine for trying to keep her from getting to Marie and Umbrella.
At some point, Nancy wished on the Skull Heart for peace between the warring kingdoms. However, there was no immediate change and years passed, during which she gave birth to Umbrella who was affected by the Skull Heart while in the womb. Upon confronting Double one night, she was told that her wish had not been pure and her transformation had merely been delayed.
After becoming the Skullgirl, she began an attack on the warring nations in the No Man's Land. Her wish was granted when their armies formed an alliance with her husband to defeat her. She was finally destroyed by King Franz's Living Weapon Eroberung, bringing the war to an end.
It was because of that tragic event that Parasoul decided that she should destroy the Skull Heart so no one could repeat the tragedy her mother met.
- It is unclear exactly when Nancy made her wish on the Skull Heart. Since the Skull Heart appears every seven years and she became pregnant with Umbrella while transforming, it is likely she made the wish either after the defeat of Selene Contiello or the Skullgirl prior.
- She is the only Renoir to not be depicted carrying a Living Weapon until she became the Skullgirl. This is most likely due to her non-violent nature prior to her transformation.
- A non-canon picture drawn by Alex Ahad of Nancy fighting Selene Contiello depicts Nancy wielding Kreig, while older concept art shows Franz wielding Todd.