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.
Burnett uses personification to make a robin into an important character in The Secret Garden. In doing so, she makes the natural world of Yorkshire seem welcoming and human to the children who are experiencing it. The robin is so intensely personified that Burnett actually has the narrator take up the robin's own story in the same way they represent the inner feelings of human characters. The following happens in Chapter 25:
At first the robin watched Mary and Colin with sharp anxiety. For some mysterious reason he knew he need not watch Dickon. The first moment he set his dew-bright black eye on Dickon he knew he was not a stranger but a sort of robin without beak or feathers. He could speak robin (which is a quite distinct language not to be mistaken for any other). To speak robin to a robin is like speaking French to a Frenchman. Dickon always spoke it to the robin himself, so the queer gibberish he used when he spoke to humans did not matter in the least.
"Speaking robin" as Dickon does here is presented here like "speaking French." While not easy, it is something that can be learned by paying enough attention if native speakers are willing to help. This moment is intended to be funny, as Burnett refers to human speech as "queer gibberish" and invokes the British cultural stereotype that a "Frenchman" would dislike hearing French from an English person.
The robin is one of Mary's first "friends" in the novel, along with the cantankerous gardener Ben Weatherstaff. The robin's personification allows for the reader to sympathize with both Mary and this hoary old character at an early stage. Mary cannot offend the robin with either her ugliness or her bad temper, as the robin doesn't understand or care about those things.
The robin also provides an additional perspective into the pastoral element of this novel, as it is a fantastical representation of a charming local animal. It is an adorable little creature with only good thoughts and experiences, making the natural world of Yorkshire and the gardens of Misselthwaite seem inviting to a young audience.