Final answer:
The narrator is most surprised by the sudden and unexpected confrontations with other people in previously thought solitary environments, illustrated by encounters with a hidden community and the abrupt arrival of soldiers.
Step-by-step explanation:
The circumstance that most surprises the narrator in the passage is the sudden transformation from being in a state of isolation and solitude to being abruptly confronted by an unexpected situation. In both snippets presented, this element of surprise stems from the sudden appearance of other people in what was thought to be a solitary environment. In one passage, the narrator finds himself facing over two hundred people who question his presence, and in the other, he is taken aback by soldiers swarming over the terrace and surrounding the house. Both scenarios depict a jarring shift from solitude to an alarming encounter with others.
Moreover, the excerpts highlight how the narrators are drawn into action through their reactions to unforeseen events—whether it be the interaction with a hidden community upon discovering a secret door, or the emergence of soldiers at a time of expected privacy. The narrative technique pulls the reader into the action by placing them directly into the mindset of the narrator as they confront these startling situations.
Finally, elements like the description of a stone door leading to an unexpected plain, the presence of a blue chamber, and the transition from a peaceful to hostile environment, all serve to immerse the reader in the story by eliciting both the element of surprise and a keen sense of place.