Colin is Master Craven's ten-year-old son. He was born in the same year in which Mary was born and the secret garden locked shut. Colin's father cannot bear to see him, as Colin reminds him of his late wife; the boy, because of his strange gray eyes, greatly resembles her, and was born only shortly before she died. Archibald Craven is ashamed of how sickly Colin is, and has forbidden the servants to speak of him. Everyone fears that he will become a hunchback and die before he reaches adulthood. Colin himself hates to be looked at, because he despises the pity and morbid fascination he inspires. He refuses to leave the manor house, and spends all his time shut up in his grand gloomy room. Like Mary, he has become fantastically tyrannical, since all his servants have been instructed to obey all of his commands without question. Mary's meeting with Colin is extremely good for him, because she is bold enough (and unsympathetic enough) to contradict him when he says that he is going to become a hunchback and die an early death. It is essential he have his negative thoughts contradicted, so that positive ones may be put in their place; this is one of the central tenets of both New Thought and Christian Science. Underlying this idea is the belief that nothing truly ails Colin's body—his disease is entirely a product of his mind. The repeated description of Colin as a "hysteric" indicates that Hodgson Burnett's preoccupation with psychosomatic illness may have another source. In 1896, the psychoanalyst Sigmund Freud and the neurologist Joseph Breuer published the Studies on Hysteria; the book was soon translated into a number of languages and gained in popularity all over the world. For Freud and Breuer, hysteria referred to a psychological disorder in which an idea or fantasy that had been repressed (made unconscious) by the mind found alternative expression in the body. While it might appear that the hysteric had an organic illness (that is, a disease of the body), Freud and Breuer maintained that its real source was in the hysteric's unconscious. For Freud, the hysteric's repressed fantasy was always sexual in nature; furthermore, he contended that the overwhelming majority of hysterics were women. Calling Colin an "hysteric" therefore feminizes him—he is weak, and frightened, and bedridden (all things a boy, presumably, should never be). Colin is positioned as Dickon's opposite: Dickon is extremely strong, masculine, and vigorous—he is of the moor, while Colin is often compared with the feminized Indian Rajah (who is described as having limp hands and being "covered with jewels").
So long as Colin shut himself up in his room and thought only of his fears and weakness ...he was a hysterical half-crazy little hypochondriac who knew nothing of the sunshine and the spring and also did not know that he could get well and could stand upon his feet if he tried to do it. When new beautiful thoughts began to push out the old hideous ones...strength poured into him like a flood.
His contact with Mary and Dickon, as well as his work in the secret garden, masculinizes and redeems Colin—he becomes "as strong and as straight as any boy in Yorkshire." It also reunited him with his father, who immediately embraces his son when he finds that he is healthy.