Mama Maureen appears in a very brief portion of the book, but the role she plays is pretty crucial: her battle with stage-four cancer is the motivating factor for Nick's return to North Carthage. She's also, however, led a pretty full life, overcoming a bad marriage to become a shoe saleslady at the mall, rediscover herself, and develop a positive attitude about hard circumstances, including her illness.
Gone Girl presents us with very few memories that Nick directly shares with us about his mother, and the majority of what we know about her comes from Amy's observations.
Maureen is the kind of mother who is overly motherly. She plans a housewarming party for Nick and Amy with no regard to whether they want one, cuts the crusts off Nick's loaves of bread even when he's a grown man, and, like Jacqueline Collings, seems to have an unrealistic view of her son as a perfect person. "'Don't be too hard on Nick,'" she tells Amy. "'I just doted on him, I babied him—how could you not? That face'"(18.5). Oh Maureen, if only you knew what Amy has in store for your son.
Maureen is also important to the novel because she provides a piece of the mysterious puzzle that is Nick's childhood. We know from Nick that his parents' marriage was void of intimacy and filled with condemnation—it was only after their divorce that Maureen was able to change from an emotionally battered shell to "the busy, warm, cheerful lady she'd be till she died" (9.30). The fact that her sister is thrilled that "the old Maureen is back" (9.30) also adds a chilling layer to her character—just like Nick, it seems his mother was squashed by her spouse.
That said, Maureen's dark past most likely explains the sincerity that Amy admires in her. She has a habit of speaking in canned phrases—"'Keep on keeping on'" (18.1); "'Make the best of a bad situation'"(18.3)—without having them sound forced. As Amy says, "the cliché stops being a set of words and turns into something real" (18.1) when it comes from Maureen's mouth. Her determination in the face of her illness is the same trait that helped her escape her marriage and be a relatively positive influence on Nick, Go, and even Amy's lives.