Nanny serves the royal family of the planet Arus as the governess to Princess Allura and the head of the domestic staff within the Castle of Lions. Her background is largely unknown, though she has stated that she acted as a mother figure to Allura, having raised and educated the young princess from childhood. At some point prior to the series, she left the castle, but she returned upon hearing that Voltron had been restored in order to resume her duties.

Nanny is defined by her overprotective and fussy nature. She is extremely cautious and worries constantly about Allura's safety, often trying to make every decision for her and prevent her from engaging in any activity that involves risk or combat. She treats Allura as though she were still a child, and she treats the Voltron pilots as if they were children as well. This maternal but domineering attitude frequently leads to humorous confrontations, as her nagging and worry clash with Allura's desire for independence and her duty as a ruler and pilot. Nanny is also notably traditional in her views, often insisting that Allura should leave fighting to the men and actively seeking a male replacement pilot for the Blue Lion rather than allowing Allura to take the role herself.

Her primary motivation is the preservation of Allura, both physically and in terms of her status as a proper royal. She believes that her role is to protect the princess from harm and to ensure that she behaves in a manner befitting her station, which she interprets as being sheltered from danger and adhering to strict propriety. This stems from her deep sense of duty and genuine affection for Allura, even if her methods are overbearing and often counterproductive.

In the story, Nanny functions as a foil to the more pragmatic advisor Coran. While Coran also fusses over Allura, he supports her growth as a leader and pilot. Nanny, by contrast, represents the old guard of courtly tradition and over-cautious protection. Her insistence on keeping Allura out of action creates conflict within the castle, especially when Allura must assert her authority as the ruler of Arus and the pilot of the Blue Lion.

Nanny's key relationships are with Allura and Coran. With Allura, she is a loving but smothering caretaker whose attempts to control her charge often strain their bond. With Coran, she shares the goal of protecting Allura but frequently disagrees with him on how that protection should be implemented, as Coran tends to be more willing to let Allura make her own choices.

The character shows limited development over the course of the series. Her core personality and beliefs remain largely static, and her role is primarily comedic and obstructive, reinforcing the status quo of the castle's domestic life. She does not possess any notable combat or supernatural abilities; her influence comes from her position as a trusted member of the royal household and her ability to intercede in Allura's personal and official decisions.