Burnett positions Dickon Sowerby, a child whom everyone loves instinctively and whose connection to Yorkshire is very strong, as a foil for the abandoned and lonely son of the Manor. Dickon's ease with people and vibrant physical health at first make Colin feel jealous and threatened, but later help him immeasurably as he seeks to heal himself and better his faulty character. When they first meet, in Chapter 19, Burnett describes their contrasting reactions to each other:
Colin had never talked to a boy in his life and he was so overwhelmed by his own pleasure and curiosity that he did not even think of speaking. But Dickon did not feel the least shy or awkward. He had not felt embarrassed because the crow had not known his language and had only stared and had not spoken to him the first time they met.
Where Dickon is easy, charming, unaffected, and quiet when the reader first meets him, Colin is at first uncomfortable, unpleasant, and gawky. Even in this situation where neither is upset, Colin is too "overwhelmed" to speak, and Dickon feels quite at ease. People actively dislike Colin, but even Doctor Craven, Colin's uncle, knows Dickon and trusts him implicitly. His face visibly "relaxes" when Mary tells him Colin will be spending time with them. The effects these boys have on the people around them are almost totally opposite, especially in the beginning of their acquaintance. Dickon's presence makes Colin want to improve himself, feeling "pleasure and curiosity" where he had previously been opposed to the idea of even meeting another child. Although he is initially jealous of Dickon's hold on Mary, Colin instantly recognizes their differences, and—instead of reacting negatively—he views Dickon's easy grace and stocky, red-cheeked health as a model for his own recovery.
As with many characters who act as foils, Dickon's goodness makes Colin's bad behavior seem much worse in comparison. This is especially true in this novel, as Dickon's family lives in poverty, and he is so much more genteel than Colin. Dickon has almost nothing and is content, and Colin has too much of everything and is miserable. When the reader compares them, Dickon is almost cartoonishly superior to Colin in every way. Dickon's body is also regularly compared to Colin's body in a way that makes Colin's figure seem even more pathetic and sympathetic. Dickon is "strong" and "fat" (meaning well-nourished), whereas Colin is "miserly" and thin.
Burnett sets up an unusual pair of characters as contrasting father figures in The Secret Garden: Archibald Craven, the Lord of Misselthwaite Manor, and the small, highly personified robin who lives in the gardens of his house. The robin's excellent, loving and attentive parenting is visible for all to see and remark on, in contrast to the public and painful absenteeism of Craven. For example, in Chapter 25 the narrator takes up the robin's perspective, describing his absolute devotion to his mate and children. Nothing is ever as important to the robin, Burnett tells the reader, as:
the immense, tender, terrible, heart-breaking beauty and solemnity of Eggs. If there had been one person in that garden who had not known through all his or her innermost being that if an Egg were taken away or hurt the whole world would whirl round and crash through space and come to an end—if there had been even one who did not feel it and act accordingly there could have been no happiness even in that golden springtime air. But they all knew it and felt it and the robin and his mate knew they knew it.
The robin's ecstatic, intense feelings surrounding his eggs are juxtaposed to those of Archibald Craven's approach to his child. While Craven avoids his child, the robin's "whole world" revolves around his family. Craven cannot stand to be around Colin because he reminds him too much of his dead wife, and leaves the boy alone to live as an invalid or to die. Such an incident would be unthinkable to the robin, who cannot even bear the idea of anyone not understanding how important his babies are to him. Such a thing would mean there could be "no happiness" for the little bird.
Colin has moments of tender suffering when he notices how attentive the robin is to his eggs. The garden itself is the site of his own father's grief and his mother's death. The fact that the robin's home and family are alive and thriving in there only makes this more poignant for the reader. When Colin and his father are reunited in the final chapter, Mr. Craven fittingly returns to find him in the garden just as the robin returns to his nest.