Why are the letters in Ovid’s Heroides described as dramatic monologues?

Ovid’s Heroides are described as dramatic monologues because they function as fictional letters written by legendary figures—such as Penelope, Dido, and Ariadne—to their absent husbands or lovers.1

These poems are considered dramatic monologues because they brilliantly exploit the rhetorical training Ovid received, specifically the exercises known as ethopoiea, or "character drawing." Through this technique, Ovid gives voice to these mythological women, allowing them to express their internal states and circumstances in a highly stylized, rhetorical manner. While the first 15 letters are solitary expressions, Ovid later transcended the inherent monotony of the format by creating pairs of letters where the lover is addressed and subsequently provides an answer, further developing the dramatic nature of the correspondence.1