In fiction, doppelgangers signal impending upheaval and raise doubt about the double’s very reality.

Evidence

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? — Naomi Klein, Doppelganger, 81

Categorization

• XREF: Connects to the reader’s library — specifically the doppelganger/double themes in Naqvi’s Home Boy (shared identity confusion) and possibly We by Zamyatin.
• BMF: Rare to claim, but the ‘double turning friends against them, destroying their career, or framing them for crimes’ maps obliquely onto the doubling in We where D-503’s double-within undermines his orderly self — a genuine cross-domain jump, though the fit is tentative.