Question

How many characters' thoughts does the reader have access to in a second-person narrative?

Answer 1

In the second-person narrative, there should be only one character's thoughts presented, usually it's the narrator's.

Answer 2

The narrator is the predominant authority in a second person narrative since they are the only element that dictates how the characters in the story should behave and how the plot moves forward. Taking account of this information, it can be inferred that the only character thoughts the reader has access to are those of the narrator, watching the story flow throught the eyes of the latter.