In Chapter 7 of the Scarlet Letter, what does it mean that Pearl took the place of an imp?
“Hester looked, humoring the child. The large, curved mirror reflected the scarlet letter in huge, exaggerated proportions. It was easily Hester’s most prominent feature: She seemed absolutely hidden behind it. Pearl pointed upwards to a similar reflection in the headpiece and smiled at her mother with her familiar elfish gleam. That look of naughty merriment was also reflected in the mirror, large and intense. Hester Prynne felt it couldn’t be the image of her own child but rather that of an imp trying to mold itself into Pearl’s shape.”
Hawthorne is playing with an image here. An imp is a little devil or demon. Another meaning might be a wild child. This symbol of the demonic just demonstrates a continued message that the author is trying to portray. He wants the audience to know that the rigid religiosity of the zealous Puritans was their downfall. Because Hester could find no grace or forgiveness for her crime, she is continually shamed by the vivid reminder of sin that is embodied in the fruit of her loin: Pearl.
What the author is directly saying in that last sentence is that although there is effort for Pearl's character to just be a child, at every turn, Hester sees the evil in her. Hester sees sin. Hester sees a little demon. The idea that the imp is trying to "mold itself into Pearl's shape" may be suggesting that the demon, the evil, and the sin are further infecting this child and taking her over.