Pearl is not meant to be a realistic character. Rather, she is a complicated symbol of an act of love and passion, an act which was also adultery. She appears as an infant in the first scaffold scene, then at the age of three, and finally at the age of seven. (Notice that three and seven are "magic" numbers.)
The fullest description of Pearl comes in Chapter 6. There, we see her at the age of three and learn that she possesses a "rich and luxuriant beauty; a beauty that shone with deep and vivid tints; a bright complexion, eyes possessing intensity both of depth and glow, and hair already of a deep, glossy brown and which, in after years, would be nearly akin to black." We learn further that Pearl has a "perfect shape," "vigor," "natural dexterity," and "a native grace," and that in public she is usually dressed in "gorgeous robes which might have extinguished a paler loveliness."
Her personality is described as intelligent, imaginative, inquisitive, determined, and even obstinate at times. She is a baffling mixture of strong moods, given to uncontrolled laughter at one moment and sullen silence the next, with a fierce temper and a capacity for the "bitterest hatred that can be supposed to rankle in a childish bosom." So unusual is her behavior that she is often referred to in such terms as "elf-child," "imp," and "airy sprite," all of which heighten her symbolism. Governor Bellingham likens her to the "children of the Lord of Misrule," and some of the Puritans believe that she is a "demon offspring."
As a symbol, Pearl functions first as a reminder of Hester's passion. Hester realizes this in the first scaffold scene when she resists the temptation to hold Pearl in front of the scarlet A, "wisely judging that one token of her shame would but poorly serve to hide another." As Pearl grows into a lovely, sprite-like child, Hester feels that her daughter's strange behavior is somehow associated with Pearl's conception and birth.
Pearl also functions as a constant reminder of Hester's adulterous act. She is, in fact, the personification of that act. Even as a baby, she instinctively reaches for the scarlet letter. Hawthorne says it is the first object of which she seemed aware, and she focuses on the letter in many scenes. She creates her own letter out of moss, sees the letter in the breastplate at Governor Bellingham's mansion, and points at it in the forest scene with Hester and Dimmesdale.
As a symbol, Pearl always keeps Hester aware of her sin. Just as Dimmesdale cannot escape to Europe because Chillingworth has cut off his exit, Pearl always keeps Hester aware that there is no escape from her passionate nature. The Puritans would call that nature "sinful." In Chapter 6, Hawthorne employs an often-used technique for that passion.
Hawthorne's handling of mirror images has both the goal of representing the passionate, artistic side of man and also the idea that life's truths can be pictured in mirror images. Hester looks into "the black mirror of Pearl's eye" and she sees "a face, fiend-like, full of smiling malice, yet bearing the semblance of features that she had known full well, though seldom with a smile, and never with malice in them." Is this her own face, never with malice, but contorted by the evil of her passion? If so, Pearl is the embodiment of that passion.
The poetic, intuitive, outlawed nature of the artist is an object of evil to the Puritans. As a symbol, Pearl represents that nature. As she looks in the brook in Chapter 19, she sees "another child, — another and the same, with likewise its ray of golden light." This child is an image of Pearl but not quite. Filled with the glory of sunshine, sympathetic, but only "somewhat of its [Pearl's] own shadowy and intangible quality," it is the passion of the artist, the outlaw. This is a passion that does not know the bounds of the Puritan village. In the forest, this passion can come alive and does again when Hester takes off her cap and lets down her hair. Pearl is the living embodiment of this viewpoint, and the mirror image makes that symbol come to life.
Hester herself tries to account for the nature of her child and gets no farther than the symbolic unity of Pearl and her own passion. A close examination of Chapter 6, "Pearl," shows the unification of the child with the idea of sin. Hester is recalling the moment when she had given herself to Dimmesdale in love. The only way she can account for Pearl's nature is in seeing how the child is the symbol of that moment. She recalls ". . . what she herself had been during that momentous period while Pearl was imbibing her soul from the spiritual world, and her bodily frame from its material of earth. The mother's impassioned state had been the medium through which were transmitted to the unborn infant the rays of its moral life; and, however white and clear originally, they had taken the deep stains of crimson and gold, the fiery lustre, the black shadow, and the untempered light of the intervening substance."
Even Pearl's clothes contribute to her symbolic purpose in the novel by making an association between her, the scarlet letter, and Hester's passion. Much to the consternation of her Puritan society, Hester dresses Pearl in outfits of gold or red or both. Even when she goes to Governor Bellingham's to plead for her daughter's custody, Hester dresses Pearl in a crimson velvet tunic. With Pearl's attire, Hester can give "the gorgeous tendencies of her imagination their full play," embroidering her clothes "with fantasies and flourishes of gold-thread." Physical descriptions of Pearl and the scarlet letter are virtually interchangeable.
Mistress Hibbins invites Hester to the forest and Hester says if the governor takes her child away she will gladly go. Their conversation reminds us that, as a symbol, Pearl is also the conscience of a number of people. First, she is the conscience of the community, pointing her finger at Hester. In any number of places, she reminds Hester that she must wear, and continue to wear, the scarlet letter. When they go to the forest and Hester removes the A, Pearl makes her put it back on. She tells her mother that "the sunshine does not love you. It runs away and hides itself, because it is afraid of something on your bosom" (Chapter 16).
Pearl is also the conscience of Dimmesdale. In Chapter 3, when Hester stands with her on the scaffold, Pearl reaches out to her father, Dimmesdale, but he does not acknowledge her. Once again on the scaffold in Chapter 13, Pearl asks the minister to stand with them in the light of day and the eyes of the community. When he denies her once again, she washes away his kiss, apt punishment for a man who will not take responsibility. She repeats her request for recognition during the Election Day procession. In her intuitive way, she realizes what he must do so to find salvation.
In the end, it is Dimmesdale's actions that "save" Pearl, making her truly human and giving her human sympathies and feelings. On the scaffold just before his death, Pearl kisses him and "a spell was broken." At that point, Pearl ceases to be a symbol. The great sense of grief, in which the wild infant bore a part, had developed all her sympathies; and as her tears fell upon her father's cheek, they were the pledge that she would "grow up amid human joy and sorrow, nor forever do battle with the world, but be a woman in it."
While Pearl functions mainly as a symbol, she is allowed to become a flesh and blood person at the end. She is a combination of her mother's passion and intuitive understanding and her father's keen mental acuity. In her, Hawthorne has created a symbol of great wealth and layers.