Perhaps the lure of first-person narrative is the opportunity to see other human beings think. To see how they think but also to see them in the middle of thinking. To catch them in their interiority. This is the appeal of having characters who have spent an entire narrative apart meeting for the first time, the moment represented from both sides. Seeing what is elided. Seeing what is misunderstood. Seeing what has been heretofore misrepresented to us, the limitations of the human subject when viewed from the outside. (Purported shabbiness is revealed to be composure, or vice versa. Confidence is anxiety. &c.) (This can also work for characters who have been separated and reunited after a long and painful journey—we see their sacrifices and so better understand their joy.) These limitations contrast with the represented interiors of the human subject, which are often limitless, or which seem limitless, or are in any case much more expansive than they could ever hope to appear to others. We can reach out as far as we want, but sometimes there is nothing there reaching back to us.
Inside, the only limit is our imagination—which too often to our detriment is not a limit at all.
Wondering how the other thinks. A process completely unknowable to us. This is part of the rupture inherent in speech, the cracks that it introduces through the uncertainty of both the abstract and the unknown. (If only we could know for “sure”!—a leap of faith is often required.) In fact, as fiction often chooses to represent, our own thinking is even often a mystery to us. What we want. What we desire. What we deny. What we are doing to ourselves or to others in the name of things which appear real to us but from the outside reveal themselves to be false: duty, propriety, social pressure… The pain, the difficulty, sometimes even violence that results—in fiction it is both easy and difficult to understand.