Margaret March-Brooke, originally Margaret "Meg" March, was the eldest March sister. In youth, she displayed vanity about her appearance, especially her fair hands, and aspired to wealth and luxury, envisioning life as a rich man's wife in a grand estate. Her susceptibility to material comforts and envy of affluent friends like Sallie Gardiner and Annie Moffat revealed struggles with discontent. Yet, she shouldered responsibility during family hardship, working as a governess and helping her mother care for her younger sisters.

Experiences like Beth's illness and exposure to high society superficiality with the Moffats matured her, teaching her to value health, family bonds, and simplicity over wealth. Her marriage to John Brooke, Laurie's former tutor, solidified this growth. Though initially poor, their union emphasized partnership and mutual respect, leading Meg to embrace dignified domestic life despite financial limits. She bore twins Margaret "Daisy" Brooke and John "Demi" Brooke, later welcoming Josephine "Josie" Brooke.

John Brooke's death left her a widow, deepening her resilience and commitment to her family. As a mother, she focused on nurturing her children. She initially opposed Daisy's romance with Nat Blake, a former Plumfield student and musician, concerned about his financial instability and suitability, reflecting her prioritization of security for her children. Her stance softened only after witnessing Demi's engagement to Alice Heath.

In later years, Meg joined sewing circles and engaged in discussions at Plumfield about women's expanding opportunities in education, careers, and suffrage. Her presence underscored her role as a steadfast matriarch within the extended March-Bhaer-Laurence family. She concluded her journey as a grandmother living near Plumfield, maintaining close ties with her sisters and the Plumfield community.