Answer:
In the poem "La Belle Dame sans Merci" by John Keats, the setting of the women on the speaker's steed is significant because it symbolizes the power dynamic between the two characters. The act of setting someone on one's horse was a medieval custom that signified a transfer of authority and control, so the fact that the speaker has placed the beautiful woman on his horse suggests that she is under his control and subject to his desires.
This setting is significant because it contrasts with the idealized view of love and beauty that the speaker has at the beginning of the poem, and highlights the destructive power that the beautiful woman holds over him. The poem's central theme is the dangers of unattainable beauty and love, and the image of the woman on the speaker's horse underscores this warning by emphasizing the power imbalance in their relationship.