WandaVision: 8 INSANE Fan Theories For The Final Episode
6. Agatha's Mother Was Zhered-Na
Since Agatha revealed her true identity to Wanda at the end of episode seven, fans have been given little hints about her past and her powers, but there is still relatively little known about her. She has lived a long time, and is clearly incredibly powerful, but she is still for the most part a mystery.
Her powers appear to be linked to a mysterious book that she keeps in her Westview basement, and while most people seem to believe this to be either the Darkhold (though this has already appeared in the MCU in Agents of SHIELD), or the Necronomicon, there is one more creepy text that it could be, the Tome of Zhered-Na.
Alive during the days of the world's first Sorcerer Supreme, Agamotto (for who the MCU's Time Stone is named), Zhered-Na foretold the destruction of Atlantis and was subsequently banished. In her exile, she founded a cult, and passed her knowledge and teachings down in the form of a cursed book.
This opens to door to the possibility of Agatha being the daughter of Zhered-Na and the witches that tried to kill her being her cult. This likely won't have a huge impact on the finale, but this technically would make her the first Atlantean to be introduced into the MCU.