|“||New Orleans is full of ghosts. Our dead are always here, hovering. When supernatural creatures die they're doomed to spend eternity alone watching the world go on without them. Of course, that's not the cause for the ancestral witches, we linger in a different way. Consecrated in the Earth, replenishing its power.||”|
The Ancestors are the totality of all New Orleans witches who have been consecrated into the earth in order to fuel the entire witch community of New Orleans. Every three centuries the Ancestors demand a sacrifice called the Harvest where they take four girls and teach them in death. However, their belief in their cause is absolute, and teach this zealism to the Harvest girls. If a witch strays from the faith, they demand that said witch pay with their life, and suffer the consequences in the land of the dead.
As it was the Ancestors who demanded the harvest ritual, which set the initial precedence for The Originals, and it was under their orders that Genevieve attempted to sacrifice Hope Mikaelson, the Ancestors act as major antagonists for the first season, and, along with Esther, the main antagonists of the final chapter.
The Ancestors are the power source of all New Orleans covens. Once a witch has died, they are consecrated, and the magic in their bones, and their spirit, are added to the ancestral power. While this restricts the witches, both living and dead, to New Orleans, it gives the coven the power, and the knowledge, of hundreds upon hundreds of witches. However, every three hundred years, the connection between the living witches, and the dead ones, begins to wane. In order to rebuild the connection, The Harvest Ritual must be performed. The Ancestors also seem to be a near divine pantheon to the living witches of New Orleans; the orders of the Ancestors are treated as divine edicts that must be obeyed.
Presumably, the Ancestors have existed as long as the French Quarter coven has.
In 1919, Papa Tunde implied that there were other Ancestral Covens in the world, as he claimed to have practiced Ancestral Magic, drawing power from the Ancestors, but was not a native of New Orleans.
In Sinners and Saints, through flashbacks, the incomplete Harvest was shown, and it was revealed that the plan of the witches was to kill Davina, and allow the magic to flow to the Ancestors, appease them, and have them resurrect the four dead witches, with the power of the coven restored.
In Aprés Moi, le Deluge, the Harvest was completed, however, the power did not return to the Ancestors, as Céleste Dubois hijacked, and used it to resurrect Papa Tunde, Bastianna Natale, and Genevieve.
In Crescent City, in response to Papa Tunde's death, Monique Deveraux is revived, and is revealed to have been schooled by the Ancestors, inheriting more power, but also their blind faith in the coven. She later kills her aunt for her lack of faith.
In Farewell to Storyville, Davina reveals that, unlike the other Harvest Girls, she was not taught by the witches in the land of the dead, but was berated and shunned by them, for her helping the vampires. The ordeal seems to have left psychological scars on her.
In The Big Uneasy, Monique is communicating with the Ancestors and they tell her it's time to resurrect Cassie, the last Harvest girl. Later on, she is about to kill Genevieve, when the Ancestors tell her not to, but they want her to kill Klaus' unborn child and will let Genevieve live.In A Closer Walk With Thee, Genevieve explains to the Harvest witches that the Ancestors do not reside on the Other Side, but in the Earth, where their magic remains. After Genevieve saves Hayley, she begs the Ancestors that she can't kill Klaus and Hayley's Unborn Baby and an unseen force makes Genevieve bleed from her eyes, nose, etc. and flings her across the cemetery.
In From a Cradle to a Grave, Genevieve, Monique and Abigail plan to sacrifice Hope Mikaelson to the Ancestors which would fuel their power for centuries. However, Klaus, Elijah, and a transitioning Hayley break through their illusion and try to stop the sacrifice. Monique and Abigail call on the full power of the Ancestors buried in the cemetery to stop the Originals. However, Abigail is killed by Klaus, breaking the power of the Ancestors and, before she can be sacrificed, Marcel saves Hope, killing Monique in the process. Held prisoner by Elijah and Hayley, Genevieve reveals that the Ancestors would not stop trying to kill Hope, because that was the deal that they had made with the most powerful witch of them all: Esther. The Ancestors have resurrect Esther and Finn to allow her to kill Hope and the other Originals.
In They All Asked For You, Finn Mikaelson is confronted in the cemetery by his brother Klaus. Finn criticized his brother for confronting him in the place where the Ancestors were the strongest. As a witch possessing another witch against his will, Klaus deduced that the Ancestors did not like Finn. He agreed with the fact that the Ancestors had little affection for him but he also told him that they hated Klaus far more. At that, Finn unleashed a wall of flames against his brother but he was able to evade them. Despite channeling the full power of the Ancestors, Finn was unable to stop his brother and was only saved by the intervention of Elijah and Freya.
Note: * indicates the witch is a former ancestor.