Veneno para las hadas

• Ana Patricia Rojo won the 1986 Ariel Award for Best Actress for playing Verónica, the orphan who convinces her wealthy new friend she's a real witch — not Best Supporting Actress, and not for playing Flavia, as is sometimes misremembered.
• The film swept that same Ariel ceremony, also taking home the Golden Ariel for Best Picture and recognition for Taboada's direction.
• Taboada shot the film with zero special effects, deliberately leaving the witchcraft ambiguous — a stripped-down, psychological approach that stands apart from the more overtly supernatural scares of his earlier film El libro de piedra.
• The production filmed in 1984 around Tlaxcala state, Mexico — including Laguna de Acuitlapilco, the old convent of Tepeyanco, and the Molino de los Reyes — not at a hacienda in Guanajuato.
• Though shot in 1984, the film sat on the shelf for two years before hitting Mexican theaters on October 2, 1986.

The fairy poison itself is never proven real — the true horror is that Verónica's invented witchcraft becomes a psychological weapon for a kid denied power by class and neglect, while Flavia, the wealthy one, ultimately answers it with real violence, proving she's the more dangerous 'witch' of the two.

Verónica may half-believe her own witchcraft, raised as she was on her nanny's superstitions and starved for validation at school — blurring the line between con and genuine belief, and turning her extortion of Flavia into a desperate bid for belonging rather than a calculated grift.

Read as a dark inversion of the fairy tale: the real monster isn't a witch in the woods, it's a wealthy child in a pretty dress whose panic turns lethal — while the orphan who only ever told stories is the one who pays for it with her life.

In a Mexico City convent school, orphaned outcast Verónica has exactly one weapon against the girls who mock her: the witchcraft her superstitious nanny swears is real. When wealthy new student Flavia arrives, Verónica sees her opening — she claims to be a genuine witch, and the awestruck Flavia becomes her devoted, increasingly terrified follower. The game escalates once the girls retreat to Flavia's family country house, where Verónica insists on brewing an actual poison to destroy the fairies, witchcraft's natural enemies, gathering snakeskin, toad, spider, and cemetery dirt for the brew. Cooking it up in the hacienda's barn loft while Flavia watches from below, Verónica's shadow twists into something monstrous — and Flavia's fear curdles into panic. She yanks away the ladder trapping her "friend" above, then drops a lit candle into the straw. Taboada strips out every special effect and never confirms whether any of it was ever real magic — just two children, one campfire story, and a fire that Flavia watches burn with a smile on her face.