Mary Lennox and Colin Craven, the central characters in The Secret Garden, are cousins who share a striking psychological resemblance. Both have been essentially orphaned—Mary through the death of her parents, and Colin through his mother’s death and his father’s subsequent neglect. Raised by servants who both dislike and fear them, they have become unruly and unpleasant, prone to tantrums when their desires are not met. These caretakers tend to their physical needs but fail to provide the love and affection they crave. Unbeknownst to them, Mary and Colin are deeply lonely, isolated, and fearful that their lives will continue to lack true, lasting happiness.

Mary starts to gain self-awareness and understand her needs when she moves to her uncle Mr. Archibald Craven's home and learns to care for herself. With no friends or toys, she begins to identify with the surly gardener, Ben Weatherstaff, and a robin abandoned by its nest mates. For the first time, she realizes her deep-seated loneliness but remains unsure of how to overcome it. With the robin's guidance, she discovers the neglected secret garden and feels a strong resolve to restore it. As she revives the garden, Mary’s physical health improves, and she gradually transforms into a lively, healthy, and happy young girl capable of seeing beyond her own needs.

Colin is introduced nearly halfway through the novel when Mary finds him secluded in his room. Colin's mother died giving birth to him after being struck by a tree branch in the garden, which led to her premature labor. Mr. Craven, unable to cope with his grief, has become a recluse and avoids his son. Though he harbors no ill will towards Colin, he cannot look at him without being reminded of his late wife. Colin, fearing he will develop a hunchback and die, is a hysterical and angry young man, deeply wounded by his father’s inadvertent rejection. He longs for companionship, needs to learn to give and receive love, and must discover how to help himself. Recognizing her own struggles in Colin, Mary confronts him, insisting that his only ailment is the weakness brought on by his prolonged bed rest. Using her own fierce temper, she challenges him to recover and introduces him to the secret garden.

Dickon, Martha's younger brother, stands in stark contrast to Mary and Colin. As a static character, he offers unconditional acceptance to the troubled children, aiding in their growth. Possessing an extraordinary, almost mystical connection with wildlife and nature, he attracts squirrels, rabbits, foxes, and lambs simply by playing his pipes. A true Yorkshire lad, he is deeply connected with nature and completely at peace with himself. He harbors no doubts, fears, feelings of isolation, or selfishness. His innate kindness provides Mary and Colin with their first experience of a positive, nurturing friendship.

Dickon's character subtly underscores the novel's themes of rebirth and redemption through nature, contributing to The Secret Garden's portrayal as a story of hope and joy realized.