Background
"Hester sought not to acquire anything beyond a subsistence, of the plainest and most ascetic description, for herself, and a simple abundance for her child. her own dress was of the coarsest materials and the most sombre hue; with only that one ornament-the scarlet letter- which it was her doom to wear. The child's attire, on the other hand, was distinguished by a fanciful, or, we might rather say, a fantastic ingenuity, which served, indeed, to heighten the airy charm that early began to develop itself around the little girl"
This quote show us that while making only humble clothes for herself, Hester makes ornate and beautiful clothing for Pearl. Her guilt over Pearl's unholy entrance into the world and her love for Pearl make Hester produce these ornate clothes for her daughter.
Physical Description
"And then what happiness would it have been, could Hester Prynne have heard her clear, birdlike voice mingling with the uproar of other childish voices and having distinguished and unravelled her own darling's tones, amid all the entangled outcry of a group of sportive children!"
"Little Pearl's unwonted mood of sentiment lasted no longer; she laughed, and went capering down the hall, so airily, that old Mr. Wilson raised a question whether even her tiptoes touched the floor."
Personality
Like I said above, Pearl is a weird and almost inhuman character. People often disagree with what part she plays in the novel; either character or symbol. While her physical characteristics don't make seem peculiar to the reader, her personality and her actions are unsettling.
"Even the poor baby at Hester's bosom was affected by the same influence, for it directed its hitherto vacant gaze towards Mr Dimmsdale, and held up its little arms, with a half pleased, half plaintive murmur."
Here, even as baby Pearl seems to recognize her father to a certain degree. She is almost like the possessed children from horror movies.
"Gazing at Pearl, Hester Prynne often dropped her work upon her knees, and cried out with an agony which she would fain have hidden, but which made utterance for itself, betwixt speech and a groan, 'O Father in Heaven-if Thou art shill my Father-what is this being which I have brought into the world!' And Pearl, overhearing the ejaculation, or aware through some more subtle channel of those throbs of anguish, would turn her vivid and beautiful little face upon her mother, smile with sprite-like intelligence, and resume her play."
Pearl has not experienced any sort of loss or any hardship. Even though Hester experiences hardship, Pearl's life is sheltered and she always is provided for and cared for by Hester. In a sense, she has yet to lose her innocence, and Hawthorne implies that one must lose their innocence before they can become fully human. Pearl's transformation from a weird and quasi-human to a full human after she experiences the death of her father, Arthur Dimmsdale.
"Pearl kissed his (Dimmsdale) lips. A spell was broken. The great scene 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. Towards her mother, too, Pearl's errand as a messenger of anguish was all fulfilled."
Creepiest Pearl Quote (said to a sailor who called her a "witch-baby"): " 'Mistress Hibbins says my father is the Prince of the Air!' cried Pearl, with a naughty smile. 'If thou callest me that ill name, I shall tell him of thee, and he will chase they ship with a tempest!'"