Holding comic and tragic simultaneously
Dark comedy's defining move is its refusal to let either the comic or the tragic register cancel the other. In most fiction, comedy and tragedy alternate or one predominates; in dark comedy, they are present at the same moment, producing a specific discomfort that is neither the pleasure of pure comedy nor the catharsis of pure tragedy. Writing this requires resisting the pull toward resolution: the impulse to either make things funnier by reducing the tragedy, or to honor the tragedy by dropping the comedy. The both-at-once effect depends on maintaining the genuine horror of the situation while finding the comedy that only that specific horror can generate. When the reader laughs and then feels slightly wrong about laughing, the dark comedy is working. When they either laugh freely or do not laugh at all, something has collapsed.