In Rappaccini's Daughter, Nathaniel Hawthorne has created very complex characters in what is a study in motive along with a study in good and evil, as well as in science and nature. Giovanni is the young protagonist; Beatrice the beautiful heroine; Rappaccini the exalted but delusional and deranged antagonist.

Giovanni is seeking greater truth but cannot prevent himself from becoming obsessed with an alluring beauty who appears to be the opposite of the lasting truth of knowledge because time and nature continually change and degrade beauty. Along with being obsessed by strange versions of familiar beauty, he also has a bit of a gullible nature that is easily influenced. As a result, he doesn't know "his own mind." These weaknesses in him, especially the weakness of not knowing his own mind, become the catalysts by which he is corrupted and by which evil actions assert themselves as he unintentionally takes a life that is beauty enmeshed in an evil shroud.

Beatrice, the embodiment of this beauty enmeshed in an evil shroud, is all goodness and, without the poisons that reared her, might be prey to the manipulating, harming forces in the world that like to prey upon the beauty, charm, innocence and openness of vulnerable women. Her father, the scientist Rappaccini, has sought to make her a bastion of strength against the dangers of life that may bring harm to defenseless women.   

Rappaccini is a credible holder of a doctoral degree and a well respected scientist who has taken a strange and unnatural turn in his scientific work. He devotes himself to creating and growing beautiful flowers that are the possessors or strong poisons. To do his work, he enlisted the help of Beatrice by raising her on the same poisons that created and raised the flowers. He created her to be their caretaker.

Hawthorne explores the ideas of what motives propel each character in addition to discussing the definition of good and evil along with the question of compatibility between Nature and science. Hawthorne underscores his discussions when Giovanni, the good young student with human weakness, becomes the slayer of the evil and poison-wrapped Beatrice who, while living, was ironically the embodiment of goodness. Giovanni and Rappaccini become more alike than they are different with the help of the jealous and envious services of the good professor from whom Giovanni seeks aid and comfort.