In the dozens of books that have been written about people who encounter their doubles, doppelgangers consistently signal that the protagonist's life is about to be upended, with the double turning their friends and colleagues against them, destroying their career, or framing them for crimes, and—very often—having sex with their spouse or lover. A standard trope in the genre is a nagging uncertainty about whether the double is real at all. Is this actually an identical stranger, or are they a long-lost twin? Worse, is the double a figment of the protagonist's imagination—an expression of an unhinged subconscious?

XREF: Connects to literary tradition from Dostoevsky's 'The Double' through Nabokov, Poe, and contemporary doppelganger fiction.

Naomi Klein, Doppelganger, loc. 81