Near the beginning of the play, how does Mrs. Linde's presence help to define Nora's character?
In the beginning of the play, the audience is first exposed to Nora, her behavior, and the dynamics of her marriage. By all accounts, Nora embodies happiness, joie de vivre, and bliss. This exposure leads to the belief that Nora's life is all put together and that she has no worries in the world.
Shortly after the beginning, in comes the character of Mrs. Linde. From the start, it is clear that Mrs. Linde is the complete opposite of Nora. Her voice is described as "dejected" and "timid." When Nora sees her, she immediately notices that Mrs. Linde has changed greatly, not necessarily for the better. Then, we hear the story of Mrs. Linde: she is alone in the world, needs employment, and longs for companionship.
When juxtaposed in the same entry scene, it is clear that Ibsen intended for Linde to be the polar opposite of Nora. The audience will form a contrasting view of the two women that will help them to define who Nora is. That is the way that Linde's presence helps to define Nora's character at the beginning of the play.
Still, another big juxtaposition will come later on in Act I, when we will witness how Linde's presence not only helps to define Nora's traits but also challenges Nora's true self to come out. It is here that Nora decides to tell her secret to Christine as a way to show that she (Nora), too, has gone through vicissitudes and sacrifices on behalf of others. It will be through this confession that Nora's character will be further delineated, and the audience will realize the kind of person that Nora is: a woman that has been socially groomed to play an expected role for which she is neither appreciated nor valued—a role which she will end up resenting.
I was your little skylark, your doll, which you would in future treat with doubly gentle care, because it was so brittle and fragile. . . . It dawned upon me that for eight years I had been living here with a strange man, and had borne him three children—. Oh, I can't bear to think of it! I could tear myself into little bits!
A Doll's House, by Henrik Ibsen, is often called the first feminist play, and concerns the emotional dissolution of a marriage.
In the first act, Nora has been seen to behave childishly with her husband, Torvald, and so it comes as a shock to the audience when she reveals to her friend Mrs. Linde that she took steps to save Torvald's life while he was ill. Her action of borrowing money and slowly paying it back with her own work flies in the face of her seeming dependence on her husband, who is unaware of her extra labors. Nora states:
"...how painful and humiliating it would be for Torvald, with his manly independence, to know that he owed me anything!" (eNotes eText, Act 1)
Although Nora plays the role, she recognizes that Torvald's ego is stronger than his love of her; an emotionally-balanced marriage would have no qualms about such a situation. This is in sharp contrast to Mrs. Linde, who works from necessity and has no husband to help, or to pacify. Later in the same conversation, she says:
"...there is something that is called, in business, quarterly interest, and another thing called payment in instalments, and it is always so dreadfully difficult to manage them ... Whenever Torvald has given me money for new dresses and such things, I have never spent more than half of it...." (eNotes eText, Act 1)
At the time, women were not expected to understand or even care about business and related topics, so for Nora to both understand and take steps to spend within a budget -- a budget that secretly includes interest payments! -- was almost unheard-of. Nora's inner character is therefore seen as stronger than her outer facade, which she forces into a mold to keep her husband's ego happy. In contrast, Mrs. Linde is outwardly more overworked, but has no need for deception, and so the emotional relief of living in truth is compared with the burden of pretense.