|“||I've... I've been hexed. And I don't know how long I have.||”|
— Kieran on The Rosary in Crescent City
The Rosary of Madness is a dark object which was cursed by two witches, Mary-Alice Claire and Astrid, under the orders of the Original Vampire, Kol Mikaelson. By appearance, it resembles an intricately carved wooden bead rosary. The Rosary was magically imbued to drive people into violent, psychopathic insanity and was one of the many ideas of Kol Mikaelson in his war against Niklaus Mikaelson and has impacted the series a hundred years after its creation, having hexed and killed Sean and Kieran O'Connell. It was one of the Dark Objects which the French Quarter Coven still possessed and not collected by Father Kieran in his secret apartment.
Throughout The Originals Series
In Sinners and Saints, it is revealed that the witches of the French Quarter are not indeed simple victims, but are after Davina due to her being a sacrifice in a ritual performed every 300 years by the French Quarter Coven. Six months ago, when the sacrificial ritual was being prepared for, four girls were chosen to be killed (with each death, the full power of an element would pour into and out of the girl's own power and move on to the next) and resurrected after being taught by the Ancestors in Limbo. Marcel, Sophie and Father Kieran would oppose the ritual. Kieran demanded to the Elders Jane-Anne, Bastianna and Agnes that they not go through with the Harvest. The witches saw this as defiance and blasphemy and as punishment (and to keep Kieran distracted), a witch Elder named Agnes used the Rosary of Madness on the Father's nephew, Sean. Sean didn't simply lose his mind, but was hexed by Agnes, which made him look like he was slowly losing it and keeping Kieran occupied like they planned. Sean's insanity extended to the point where he became murderous, killing everyone of the students in St. Anne's and then cut of his own head. While Kieran was taking care of Sean, he informed Marcel of the witches' plans and it ultimately lead to the Harvest's premature outcome.
In Crescent City, Bastianna, one of the Elders of the French Quarter Coven, meets Kieran at the church. Kieran notices that the witch (who had previously been killed by Marcel's vampires after the Harvest's failure). Bastianna grabs his hand with the beads of madness in her hands and chants, "Toursion fou, morte de l'espirit!" and then rubs his thumb and a cross symbol materializes like a brown tattoo on it and she tells him to "Give your nephew Sean my regards when you see him in Hell." and leaves.
Later that same day, Bastianna informs Kieran and Cami that it is punishment and his ensuing death will atone for the part he played in stopping the Harvest the first time round.
In The Big Uneasy, Camille begs Genevieve to undo the hex that was placed on Kieran as his condition has deteriorated. After being gifted with something that touched her, Geneviève tells her that there might be a way to save Kieran. Later, Klaus pisses Geneviève off and in smug revenge, Geneviève admits that she only gave Camille false hope and that if there was ever hope at all, it is gone now, implying that she will only not undo the hex to spite Klaus.