This is one of my favorite sci-fi short stories, period. Up there would be the one that inspired Arrival (I don't recall the name), and The Last Question.
This one was great, because it's not clear until the very end whether the character is going through increasing levels of paranoia, or dealing with an adversary. The way the dénouement is stitched together (literally) was such a shock. I love it.
> the one that inspired Arrival (I don't recall the name),
It's called "Stories of your life". Highly recommend both the book that includes it ("Stories of your life and others") as well as Exhalation. Ted Chiang is superb.
For the longest time, I was wondering if thw stock market schemes, feeling followed, seeing things in patterns, was just paranoia and paraeidolia. Would be plausible within the story!
> it's not clear until the very end whether the character is going through increasing levels of paranoia, or dealing with an adversary
Er, which one do you think it resolved as? Your phrasing suggests you went from doubt to believing the narrator is reliable and sane. I was and am convinced in his reliability; yet, he fell for a painfully obvious ploy by the adversary, which is not terribly consistent with superintelligence. Nevertheless I understand the story to be, in-universe, reliable, but from outside, intentionally following narrative tropes consistent with mental illness. Other tropes include "there's something in the jab", "CIA is after me", "I have become the renfield of a hidden adversary".
So there's a lot of evidence for the opposite interpretation, that the protagonist is simply ill the whole time. This interpretation has the distinct advantage that falling for the attack was truly a flaw on the part of the protagonist (qua confabulator, I suppose) rather than the narrative or the author. In fact I can't really say why I don't adopt this as my preferred interpretation; perhaps a bias for my original interpretation, or skill on Chiang's part in convincing the reader of the less plausible explanation through, what, sheer sympathy?
This one was great, because it's not clear until the very end whether the character is going through increasing levels of paranoia, or dealing with an adversary. The way the dénouement is stitched together (literally) was such a shock. I love it.