Grete is a central figure in the story, operating under the code name Daughter Dearest, a name she chose herself to reflect a deep-seated wish to be loved and accepted. She is an eighteen-year-old girl with a tall, slender build and a glossy red bob haircut. Her most distinguishing feature is a large, dark birthmark or scar that covers half of her face, which she keeps hidden beneath a mask. Her appearance is often described as having a fragile, almost ephemeral quality, like a delicate glass sculpture.

Grete possesses a calm, ladylike demeanor and a brilliant tactical mind. She is highly intelligent and serves as the strategist for her team, capable of devising elaborate plans in a matter of seconds. Despite her sharp intellect, she is self-conscious and tends to downplay her own abilities. However, this quiet exterior masks a deep well of trauma. Grete suffers from severe androphobia, a fear and dislike of men, which stems from a childhood of relentless verbal abuse from her father and older brother. Her family, who were politicians, rejected her due to the scars on her face, deeming her unfit for high society and an object of disgust. She was effectively abandoned when her father forced her to enroll in a spy academy at the age of thirteen, framing it as a recovery from an illness to the public.

Her backstory is the key to understanding her motivations. Having never felt loved by her family, Grete's primary drive is to find acceptance and affection. This longing is fulfilled when she meets Klaus, the leader of the Lamplight team. During an accidental encounter, Klaus saw her unmasked face and, instead of reacting with revulsion, he told her she was beautiful. This single act of kindness became a turning point, and Grete developed an intense, undying romantic devotion to him. Klaus is virtually the only man she can interact with without physical and emotional distress.

Her role within the story is that of the team's master planner. Her notable abilities are a perfect complement to her strategic role. She is a master of disguise, able to flawlessly mimic another person's appearance, voice, and mannerisms after seeing them. This talent is so refined that she can even craft realistic masks. Combined with her ability to perfectly replicate voices, she is a formidable infiltration specialist. However, her androphobia is a critical weakness that can paralyze her in missions requiring interaction with unfamiliar men. When Klaus's safety or affection is on the line, she has been shown to overcome her fears and display surprising bursts of capability and determination.

Her relationships with other team members add further depth. She looks up to her teammate Thea as a mentor in matters of love and seduction, diligently taking notes during Thea's more provocative stories to try and apply them to Klaus. With another teammate, Olivia, she shares a bitter rivalry rooted in the differing philosophies of their respective teachers, though she has also shown moments of genuine sympathy for her.

Throughout the narrative, Grete undergoes significant development. She evolves from a self-loathing academy washout, unable to pass any exam involving male interaction, into a brilliant and reliable spy. Her devotion to Klaus is a primary catalyst for this change. While she is intensely infatuated, often misinterpreting his innocent remarks as romantic or sexual and making bold, sometimes awkward, advances influenced by Thea’s advice, she is also self-aware. She understands that her feelings border on dependence but respects Klaus's autonomy, vowing to do right by him even if her love remains unrequited. Klaus, for his part, comes to trust her deeply and, while he admits he may not be capable of romantic love, promises to always love her as family.