What can you infer about how Torvald and Nora behave toward each other based on the stage directions in A Doll's House?
From Act I we can infer many things. First, that Nora is secretive with her husband. Notice that, from the beginning, she hides things from him, such as the macaroons that he gets on her for eating.
In turn, he acts like a teacher, or a father, who needs to remind his "child" about the evils of candy eating.
Torvald: [wagging his finger at her]. Hasn't Miss Sweet Tooth been breaking rules in town today?
While the saccharine verbal exchanges between the couple would be cringe-worthy to the realistic ear, there is a lot to be said about the non-verbal cues that Nora and Torvald exert on one another, as evidenced in the stage directions.
For example, at one point, Torvald actually goes up to Nora to gesticulate something tantamount to an ear-pulling while he scolds Nora for suggesting that they borrow money. He also calls her an airhead in the process, by the way.
Torvald: Nora! [Goes up to her and takes her playfully by the ear.] The same little feather head!
As we get deeper into the play, and get to know Torvald's character better, we will realize that this ear-pulling may very well be Torvald's own way to act out deeper, hidden emotions; he is condescending to Nora in every way because he feels superior to her.
Torvald: You can't deny it, my dear little Nora. [Puts his arm round her waist.] It's a sweet little spendthrift, but she uses up a deal of money. One would hardly believe how expensive such little persons are!
Comparatively, Nora's actions show that she allows Torvald to feel superior to her because she sees that behavior (hers) as a form of respect and admiration toward the provider of the household. It is an ancient marital system, but it was the expectation.
Nora [playing with his coat buttons, and without raising her eyes to his]. If you really want to give me something, you might--you might--
Helmer. Well, out with it!
Nora [speaking quickly]. You might give me money, Torvald.
Therefore, the tone is set from Act I. It shows very clear dynamics between Torvald and Nora in the way that they have both agreed to conduct their marriage. Torvald is the dominant and Nora is the submissive. Torvald is a parental figure and Nora is the mischievous, funny little kid that charms the household. She is, after all, a doll in all but name.