We think Miss Betsey Trotwood says it best when she describes Mrs. Copperfield as "a very Baby" (1.18). Miss Betsey is commenting on Mrs. Copperfield's appearance – her big blue eyes, her flossy golden hair, her childlike face – but she's also babyishly irresponsible. Indeed, before marrying Mr. Copperfield, Mrs. Copperfield works as a nursery-governess – a nanny. So, even when she is working to support herself, Mrs. Copperfield is strongly identified with babies and children. Her behavior in the novel reflects this association of ideas. Indeed, Mrs. Copperfield dies as she lives: Peggotty comments that she passes away "like a child that had gone to sleep" (9.103).
Mrs. Copperfield is barely twenty when she gets married; her husband is a man twice her age and in poor health. Widowed before her son is even born, Mrs. Copperfield is left to raise David with the help of her housekeeper, Peggotty. When Peggotty tries to warn Mrs. Copperfield that Mr. Murdstone, her new boyfriend, is not a good man, Mrs. Copperfield throws a huge tantrum: "Was ever any poor girl so ill-used by her servants as I am!" (2.49), she exclaims. But she soon makes up with Peggotty and it's as though the whole fight never happened. This cycle happens over and over again – Mrs. Copperfield is quick to get angry and quick to forget about it. But she never takes advice and she refuses to do anything against her own wishes.
So, we get the sense that Mrs. Copperfield is flighty, easily distracted, and spoiled. She means no harm, but she also doesn't have the strength of character to resist a clever, brutal fellow like Mr. Murdstone. Mr. Murdstone flatters Mrs. Copperfield: when David repeats to his mother that Mr. Murdstone called her "bewitching" (2.91) and a "pretty little widow" (2.93), Mrs. Copperfield blushes, laughs, and is generally very pleased. It's these compliments that bring Mrs. Copperfield to accept Mr. Murdstone's proposal of marriage even though her most trusted advisor, Peggotty, can see something is wrong with the man.
Once Mrs. Copperfield is finally married to Mr. Murdstone, the danger of her childish manners really becomes clear. Once they are married, she is totally trapped: there is no way for her to get away from the cruel authority of Mr. Murdstone. Mr. Murdstone immediately starts scolding her, playing a father figure to his new, young wife.
When David comes home from his first visit to Yarmouth, he finds Mr. Murdstone married to his mother and starts to cry. Mrs. Copperfield starts her usual fussing: "Davy, you naughty boy! Peggotty, you savage creature! [...] What a troublesome world this is" (4.10). In response to her tantrum, Mr. Murdstone replies, "Firmness, my dear!" (4.12).
This response – "Firmness!" – becomes the motto of Mr. Murdstone's. Whenever Mrs. Copperfield starts to cry, Mr. Murdstone mocks her for it and shuts her down. And whenever Mrs. Copperfield shows any kind of affection to Peggotty or to her own son, Mr. Murdstone mocks her for it and shuts her down. Eventually, he bullies Mrs. Copperfield into believing that David is a bad boy and must be sent away to school. Mrs. Copperfield comments to Peggotty that she is "a weak, light, girlish creature, and that [Mr. Murdstone] is a firm, grave, serious man" (8.92). Thus, Mr. Murdstone must know better than Mrs. Copperfield does, even though David is plainly miserable.
But all of Mr. Murdstone's firmness, graveness, and seriousness finally wear Mrs. Copperfield out. She bears Mr. Murdstone a son, a baby that never gets a name in the novel, and the two of them waste away together. Mr. Murdstone's brutality eventually destroys Mrs. Copperfield. And while David loves and pities his mother, it's clear that he resents her for the weakness that allowed Mr. Murdstone into their lives in the first place.
David describes her "pettish willful" (4.10) manner, meaning that Mrs. Copperfield is cranky, irritable, and stubborn. Mrs. Copperfield is a pretty young woman, but she also has the kind of moral weakness that makes her a poor choice for head of any household. Mrs. Copperfield also foreshadows David's own marriage to Dora Spenlow, who is equally childlike, foolish, and unprepared for family life. For some interesting contrasts to these women characters, check out our thoughts on Agnes Wickfield and Miss Betsey Trotwood; also see our "Theme" discussion on gender.