The narrator of "Rappaccini's Daughter" is of the third person limited omniscient variety. This means that the narrator is not a participant in the events that take place in the text and does not use the first person pronoun "I"; this also means that the narrator can only report the thoughts and feelings of one character, and in this case that character is Giovanni Guasconti. As a result of this, when Giovanni is confused about or frightened of something—for example, when he first sees Rappaccini conducting himself with such "caution" while he tends to the garden—this is all that we know too.

Because of this style of narration, we do not know what Rappaccini is thinking, or what Beatrice, his daughter, or Professor Baglioni, his rival, is thinking (unless they speak it aloud). If Giovanni is taken advantage of or manipulated by someone without his being aware of it, then we may not be aware of it either; we can only guess. In some cases, we know only as much as Giovanni himself does, and this includes his knowledge of himself as well. When Giovanni's own nature begins to change, as he becomes poisonous as well, he does not see that he has become "the subject of one of Rappaccini's experiments," as Baglioni suggests. Nor does Giovanni realize that Baglioni's pride might compel him to try to hurt Rappaccini by using Giovanni. This creates dramatic irony, when we learn things that Giovanni himself does not know, heightening the tension in the story.