It's still raining in the morning, so Mary stays inside. Martha comes to sit with her in the afternoon and notices immediately that there's something bothering Mary. Mary admits outright that she found Colin. At this, Martha looks terrified and says that she'll lose her job, but Mary assures her that Colin was happy to see her. Martha is convinced that Mrs. Medlock will be upset at the very least, but Mary firmly says that Colin wants to keep it a secret just between them for a while and reminds Martha that she and Mrs. Medlock are to do what Colin says. She also mentions that Colin seems to like her.
Martha's fear tells the reader that Misselthwaite Manor operates on the understanding that secrets are to be kept at all costs, to the detriment of the health of people like Martha. This shows that everyone, including the staff, suffer from this kind of secret keeping. Mary's willingness to confide in Martha, on the other hand, shows that she now believes fully in Martha's trustworthiness.
Martha insists that Mary bewitched Colin, and Mary asks if Martha is talking about Magic. She then asks what's wrong with Colin. Martha explains that Mr. Craven was so upset after Mrs. Craven died, he wouldn't see baby Colin and insisted that the weak baby would certainly die or be a hunchback. She says that Colin isn't a hunchback yet, but they're afraid his back is weak. Martha mentions the London doctor, who insisted that Colin was fine but spoiled. Mary agrees with this assessment, and Martha talks about how nasty he can be and how ill he's been. She says that Mother believes a child kept indoors like Colin can't possibly live.
Notice that although Martha says that baby Colin was weak, they only believed that he was truly ill because Mr. Craven insisted it was true. This speaks to the power of these negative thoughts, as Mr. Craven has essentially led his household into a ten-year ruse to support his belief that his son will die. The fact that this all happened because Mrs. Craven died reinforces that this is something that stems from grief, which suggests that they can heal from it.
Mary muses that it might do Colin good to get outside to see things growing, but Martha says that they took him outside once to see roses and it was a disaster: he yelled at a gardener and cried himself sick. Mary remarks that if Colin gets angry with her, she won't go see him again, but Martha says that Colin always gets his way. Martha runs off when she hears a bell but returns a few minutes later to take Mary to Colin.
Colin's earlier tantrum about the roses indicates that at that point, he wasn't ready to begin growing like the roses. Mary's unwillingness to see Colin if he's going to be mean to her suggests that because of her own haughty and selfish nature, Mary is uniquely positioned to give Colin a taste of his own medicine.
Colin is settled among cushions when Mary arrives. Mary mentions Martha's fear of being dismissed, so Colin summons Martha. He curtly reminds Martha that she must do what he says, and he promises to send Mrs. Medlock away if she gets upset with Martha. Martha curtsies and leaves, and Colin notices Mary looking at him in awe. She tells him that she once saw a young Rajah in India who spoke to people like Colin just spoke to Martha, and then she says that Colin is very different from Dickon. Mary tells Colin about Dickon's way with animals and how he loves the moor. Colin thinks that the moor is dreary and Mary says that she used to think so too, but hearing Dickon and Martha talk about it made her like it.
The way that Mary compares Colin to the Rajah she saw in India isn't a flattering comparison, especially given the way that the novel portrays India as a place where people cannot properly grow and develop. This suggests that in some sense, Colin has been stuck in a dreary existence that resembles Mary’s isolated life in India. Introducing Colin to the idea of someone like Dickon has the effect of showing Colin that not everyone is like him, and yet, they can still be interesting.
Colin laments that he never sees anything because he's sick, and Mary points out that he never leaves the room. They discuss him going outside, but Colin insists that he can't because he's going to die. Mary is unsympathetic and says that she doesn't want Colin to die. Colin insists that everyone, especially Dr. Craven and the servants, want him to die. Mary asks what the London doctor said. Colin says that the doctor insisted that if Colin wanted to live, he would. Mary suggests that meeting Dickon, who speaks only about living things, might put Colin in the mood to live. She encourages Colin to speak only about living things.
Mary's pep talk begins to shift Colin's thinking towards something more positive. Especially when Mary learns that the London doctor said much the same thing, it shows the reader that there's actually nothing wrong with Colin except for his negative thoughts. Notably, Mary is able to have this no-nonsense conversation with Colin because her own selfishness makes her unsympathetic to him; she wants him to be happy because now, she likes being happy.
Mary and Colin spend hours talking about Dickon, the moor, and Mrs. Sowerby's twelve children. They giggle like normal children, and after a while, Colin notes that they're cousins. This makes them laugh even more and as they do, Dr. Craven and Mrs. Medlock walk in. The adults look shocked, but Colin calmly introduces Mary to them and says that he likes talking to her. Dr. Craven checks Colin's pulse and declares him too excited, and Colin threatens to get even more excited if they send Mary away. He asks that Mary have tea with him, which makes the adults exchange a worried look. Mrs. Medlock offers that Colin does look better than he did earlier.
Though there's no indication that Dr. Craven is a truly evil character, suggesting that Colin should spend all of his time alone and not speak to Mary is a way for Dr. Craven to keep Colin from getting any better. Readers should also remember that Dr. Craven is next in line after Colin to inherit the manor, which may be why he’s so eager for Colin to waste away. On another note, when Mary and Colin have so much fun talking about the moor and Dickon specifically, it suggests that talking about nature can have almost as much of a healing effect as actually being out on it.
After the adults confer in the hallway, Dr. Craven reminds Colin to not forget that he's ill and easily tired. Colin tells him that he wants to forget those things, and Mary helps him do so. Dr. Craven sighs as he leaves, though he admits to himself that Colin looks brighter.
Colin's insistence that he wants to forget his illness suggests that he's turning the corner and recognizes that if he stops thinking the negative thoughts, they'll stop having any power to dictate the state of his health.