Pearl at the beginning of this Chapter is described as being separate from Hester and Dimmesdale, as she stands on the opposite side of the brook from them. What is key to note though, is that in the last Chapter Hester has torn the scarlet letter from her breast, and it is this that makes Pearl so upset and explains why she is reluctant to come and be introduced to her father, Dimmesdale. Even though Hester threatens her, she still refuses to jump over the brook, and her agitated nature becomes worse and worse:
But Pearl, not a whit startled at her mother's threats any more than mollified by her entreaties, now suddenly burst into a fit of passion, gesticulating violently, and throwing her small figure into the most extravagant contortions.
Interestingly, and perhaps slightly ironically, Pearl, who has been described up until this stage as an "elf-child" who seems to exist beyond the pale of moral discrimination, now acts as a focus for the distinction of right and wrong. This is something that she achieves above all through her very being, as her presence reminds her parents of their "sin." It is entirely fitting then, that as her parents are trying to act as if they haven't sinned and are in effect denying the existence of Pearl, that she should remind them of her existence in the most forceful way she can.