Maggie Tulliver is the protagonist of The Mill on the Floss. When the novel begins, Maggie is a clever and impetuous child. Eliot presents Maggie as more imaginative and interesting than the rest of her family and, sympathetically, in need of love. Yet Maggie's passionate preoccupations also cause pain for others, as when she forgets to feed Tom's rabbits, which leads to their death. Maggie will remember her childhood fondly and with longing, yet these years are depicted as painful ones. Maggie's mother and aunts continually express disapproval with Maggie's rash behavior, uncanny intelligence, and unnaturally dark skin, hair, and eyes. Yet it is only Tom's opinion for which Maggie cares, and his inability to show her unconditional love, along with his embarrassment at her impetuosity, often plunges Maggie into the utter despair particular to immaturity.
The most important event of Maggie's young life is her encounter with a book of Thomas a Kempis's writings, which recommend abandoning one's cares for oneself and focusing instead on unearthly values and the suffering of others. Maggie encounters the book during the difficult year of her adolescence and her family's bankruptcy. Looking for a "key" with which to understand her unhappy lot, Maggie seizes upon Kempis's writings and begins leading a life of deprivation and penance. Yet even in this lifestyle, Maggie paradoxically practices her humility with natural passion and pride. It is not until she re- establishes a friendship with Philip Wakem, however, that Maggie can be persuaded to respect her own need for intellectual and sensuous experience and to see the folly of self-denial. Maggie's relationship with Philip shows both her deep compassion, as well as the self-centered gratification that comes with having someone who fully appreciates her compassion. As Maggie continues to meet Philip Wakem secretly, against her father's wishes, her internal struggle seems to shift. Maggie feels the conflict of the full intellectual life that Philip offers her and her "duty" to her father. It is Tom who reminds her of this "duty," and Maggie's wish to be approved of by Tom remains strong.
The final books of The Mill on the Floss feature Maggie at the age of nineteen. She seems older than her years and is described as newly sensuous—she is tall with full lips, a full torso and arms, and a "crown" of jet black hair. Maggie's unworldliness and lack of social pretension make her seem even more charming to St. Ogg's, as her worn clothing seems to compliment her beauty. Maggie has been often unhappy in her young adulthood. Having given up her early asceticism, she longs for a richness of life that is unavailable to her. When she meets Stephen Guest, Lucy Deane's handsome suitor, and enters into the society world of St. Ogg's, Maggie feels this wont for sensuousness fulfilled for the first time. Stephen plays into Maggie's romantic expectations of life and gratifies her pride. Maggie and Stephen's attraction seems to exist more in physical gestures than in witty discussion, and it seems to intoxicate them both. When faced with a decision between a life of passionate love with Stephen and her "duty" to her family and position, Maggie chooses the latter. Maggie has too much feeling for the memories of the past (and nostalgia for a time when Tom loved her) to relinquish them by running away.