The incarnation of Hester and Arthur Dimmesdale's sin of adultery, Pearl has an other-worldliness about her. She is capricious and the Puritan children do not like her because she is so different from them, "she never created a friend." Indeed, she is more symbol than she is human; moreover, it is not until her father kisses her on the scaffold at the novel's end that Pearl becomes truly human as "a spell was broken" and her "errand as a messenger of anguish was fulfilled."
Before this part of the novel, Pearl is described as an "elf-child" and an "airy-sprite" who plays an active role in reminding her mother of her sin. Often she pelts Hester's breast with some flowers or seaweed. In Chapter VII at the mansion of Governor Bellingham, she laughs at the distortion of the scarlet A in its reflection in the breastplate of the suit of armor. Her repeated questions about the scarlet letter cause her mother in Chapter XV to deny the letter's significance. In Chapter XIX, Pearl refuses to cross the brook after her mother has tossed away the letter: she shrieks in a fit of passion and will not cross until Hester reattaches the symbol to her garment. Truly, throughout the narrative, Pearl acts as the conscience of her mother: "Above all, the warfare of Hester's spirit at that epoch was perpetuated in Pearl."
The place to look at in order to find the answer to this question is Chapter Six of this novel. This whole chapter focuses on the character of Pearl, Hester's daughter that came from her adulterous union with the stranger who is only identified as the novel develops. In this section of the novel, Pearl's appearance is identified, but also her character is explored, and as the following quote makes clear, there is certainly more to Pearl than one might suspect:
The child could not be made amenable to rules. In giving her existence, a great law had been broken, and the result was a being whose elements were perhaps beautiful and brilliant, but all in disorder; or with an order peculiar to themselves, amidst which the point of variety and arrangement was difficult or impossible to be discovered.
The disposition of Pearl as a character therefore reflects her beginnings as a child who was conceived and born outside the sanction of society and through an illicit union. In her character she seems unable or unwilling to conform to society's constrictions, just as her mother did not conform. This is a picture of Pearl that continues to be developed as her character is further explored in the novel.