Narrator
The second stanza of the poem is narrated from neither of the main character's dialogue. Not much personal information is revealed about the narrator except for his or her third party view of the lovers. The poetic language of the narrator implies no strong tether to the strict reality of events which he or she is witnessing.
Him
He is the morally prescriptive one. When his lover tempts him to wander down the hill on the easier path, he refuses. He believes that the way to hell and corruption is easy but once taken cannot be retraced to return uphill. Compared to her, he is caught up in the romance of their environment. He views everything around them through the lens of beauty and wonder, but he is suspicious of the downhill path.
Her
She is the impetuous one who determines to take the downhill path. Resisting her lover's warnings, she is too tempted by the ease of the downhill path to resist. Even if the path leads to hell, she wants to take it. She's dismissive. In a similar vein, she answers all of her lover's childlike questions of wonder with sharp and logical responses. She sees the world as black and white, one way only. She misses much fo the beauty to which her lover is sensitive.