Chapter two explores the psyche of the core characters, as well as the thin line that divides childhood from the teenage years. When Miss Brodie tells the girls about Hugh Carruthers, her love who died in WWI, as well as a bevy of other lovers she has had, the Brodie Set becomes enamored with the idea of sex and love. 

While fascinated by adult themes—so much so that they write romantic stories about Carruthers and Miss Brodie being together—they also still believe in childish fancies, like being able to dig a hole to Australia or that sex is inherently immoral and dirty. The juxtaposition of their internal lives speaks to the confusion of youth and the fine division preserving childhood innocence. 

The chapter returns to the future to discuss Mary’s destiny as a sad, aimless woman who dies a pointless death. Shortly before she perishes, she realizes the only time she was ever happy was when under the tutelage of Miss Brodie. Adding to her sorrow, Mary has not felt real love and worries she has not experienced her prime. The narrative turns to the day of the fire: While on leave from the Women's Royal Navy Service, she stands in the hallway of the burning hotel, unable to see the exit through the smoke or follow the noise of those trying to guide her over the din of the fire. Eventually, she asphyxiates in the hallway, a victim of her own passivity. 

Shifting back in time, the narrative turns to ten-year-old Sandy, who shows an uncanny level of awareness for her age and spends much of her youth pondering how Miss Brodie and the Brodie Set function as individuals and as a collective. She realizes at the age of ten that she should be happier than she ever has or will be. But she does not know what that type of happiness might look like. 

In Sandy’s talks with Jenny, they decide that their parents traded in their elusive “prime” for sex. When they consider the fact that a teacher, Mr. Lloyd, just had a baby, they conclude that he too has "committed sex." This language shows that the young girls are deeply uncomfortable with their sexuality, a fact reaffirmed when Sandy insists she will never have sex, to which Jenny agrees. Another flash-forward reveals that Sandy stayed true to her word, becoming a nun named Sister Helena.

Sandy draws parallels between Miss Brodie and the fascists she likes to teach about: Miss Brodie is the "head," and the girls are the "body" or "marching soldiers" who follow her lead. Sandy realizes she and the other girls are not very nice to Mary because Miss Brodie is not friendly to Mary either, seeing the tie between Miss Brodie’s behavior and the Brodie Set’s reflection of it. She recalls how Miss Brodie said she will never be "elite or the crème de la crème," which likely plays a significant role in her choice to become a nun, as Sandy, like the other girls, is significantly influenced by Miss Brodie.

Sandy has peculiarities about her, though, that make her different from just one of Miss Brodie's soldiers. She has no interest in romance and believes that if one actually thought about having sex, then no one would go through with it. She also sees the world differently than the other girls, indicating her characteristic self-determinism—out of place in a group like the Brodie Set. 

The crux of this chapter is the discussion of Miss Brodie's peculiarities. The school sees her as an "Edinburgh spinster of the deepest dye," which, at the...