I believe that would be irony
Answer:
This question lacks context but I will try to answer with what I can. When a poem juxtaposes, it places two different things side by side so you can compare and contrast, giving the poem an interesting effect. The poem might be suggesting that there are many similarities in the two subjects being juxtaposed as well as differences.
Subjects are "Janet" and "Peter". A subject is a person place, thing or or even idea in a sentence.
Verbs are "drove" and "camped". A verb is a word used to describe action.
Answer:
The spooky black river is the subject.
