The device is documented: a terracotta wheel from Akanthos, 350 to 300 BCE, carries five wrynecks; sorceresses tied the bird to a spinning wheel while pronouncing love spells, targeting unfaithful lovers. The wryneck, Jynx torquilla, twists its neck in a full circle and sings like a flute when displaying. Pindar has Aphrodite give the iynx to Jason, turning it with incantations to enflame Medea. The bird ceased to be used and the word moved to the wheel, then to the charm, then, in 19th-century American slang, to the curse itself.
The myth explains the charm by punishing its inventor: Iynx, daughter of Pan and Peitho or Echo, enchanted Zeus himself, or Io, with her wheel, and Hera's answer was metamorphosis, the sorceress becoming her own device. The pattern is the archive's familiar one, magic tools with divine pedigrees and mortal consequences: the charm outlives the charmer, and the punishment becomes the brand. Jason got the wheel from a goddess. Medea got the flames. The nymph got birdhood. Everyone got exactly the love-magic's terms.
The claim: every love spell is a curse to the beloved, and jinx's drift from charm to curse is the target's perspective finally winning the word; the iynx was always coercion, one person spinning another's will on a wheel, and the language eventually admitted it. Verdict: the Greek texts are frank, the charm forces the lover back against their will, and the modern word's negativity is the honest reading. The archive's spellwords all carry this torsion: the spell is power to the caster and weather to the target. Name it from the wrong end and it becomes a jinx. From the right end, it is still marketed as charm.
If the charm was a bird on a string, what was the spell: the words, the wheel, or the cruelty?