Annette Burnier is the twelve-year-old protagonist of the story, living with her family in a small, poor village nestled in the Swiss Alps. Her life has been marked by hardship from a young age, as her mother passed away while giving birth to Annette's younger brother, Daniel, whom she affectionately calls Dani. This tragedy has forced Annette to mature quickly, and she has taken on a significant caregiving role for her five-year-old brother, acting as a surrogate mother to him.

Despite her difficult circumstances, Annette is known in the village as a sweet-natured, hard-working, and determined girl who is a top student in her class. Her diligence and strong will earn her respect from her peers, including the school bullies who prefer to avoid provoking her anger. She is a spirited and energetic tomboy who is not afraid to stand up for herself or others, and she enjoys outdoor activities as much as domestic tasks like sewing and housework. However, this strong-willed nature is accompanied by a hair-trigger temper and a capacity for being stubborn, spiteful, and prone to harsh arguments. Her decisions are often driven by her own intense emotions, and she can be egocentric, struggling to admit when she is wrong.

The central conflict of Annette's story arises from her deep bond with her best friend, a boy named Lucien Morel. Their friendship is severely tested after a tragic accident in which Lucien is unwillingly responsible for Dani falling from a cliff, an accident that breaks the young boy's leg and threatens to leave him permanently crippled. Overwhelmed by a torrent of anger, resentment, grief, and jealousy, Annette blames Lucien for the tragedy and refuses to forgive him for a long time. Her resentment festers, causing a dark change in her personality that stands in stark contrast to her outwardly good behavior as a doting sister and diligent student. This internal bitterness leads her to a moment of cruelty where she deliberately breaks an intricately carved wooden horse that Lucien had made for a competition, an act she immediately regrets. This moment becomes a turning point, sparking her self-realization about the destructive nature of her prolonged anger and grudge-holding.

Annette's role in the story is that of a flawed heroine whose journey is defined by learning to overcome her powerful negative emotions. Her primary motivation throughout is the well-being and protection of her beloved younger brother, Dani, whose cheerful and forgiving nature serves as a constant reminder of her own underlying goodness. Her key relationships are central to her development. Her father, Pierre Burnier, is a kind and compassionate widower who does not blame Lucien for the accident and consistently urges Annette to let go of her anger. Her great-aunt, Claude Martha, moves in to help the family and acts as a rational and patient conscience for Annette, offering moral guidance and gently questioning her resentment. It is through their wisdom and her own painful self-reflection that Annette eventually finds the strength to forgive Lucien, leading to a reconciliation that rekindles their friendship and allows her to move from a state of resentment toward emotional healing.

While not possessing any extraordinary abilities, Annette is notably capable in various practical skills. She is a hard worker and a top student, demonstrating intelligence and determination. She is adept at domestic tasks, though she was initially a poor cook, once making a soup so sweet that her father refused to eat it, but she later improves her skills with her great-aunt's help. Her life in the Alps has made her outdoorsy and resilient, blending a tomboyish spirit with an ability to handle traditionally feminine chores. Her most significant "ability," however, is her profound capacity for emotional growth, as she ultimately learns to master her temper and pride to choose the difficult path of forgiveness.