WARNING: SPOILERS for WandaVision ep 7, 'Breaking The Fourth Wall'.
After weeks of speculation over exactly who is responsible for what is going on in Westview, New Jersey, WandaVision's seventh episode, 'Breaking The Fourth Wall', shook things up with the biggest reveal so far. Wanda's 'helpful' neighbour, Agnes, is really a witch, Agatha Harkness, and she has been responsible for just about everything that has gone wrong in Wanda's supposedly idyllic sitcom world, including, to the horror of many fans, the death of Sparky.
The possibility of Agnes being Agatha Harkness, a long running supporting character in Marvel Comics, has been a popular theory among comic fans since before the show began airing, so for them, the reveal was welcome, even if not a surprise. Those with less comics knowledge, however, may have been left scratching their heads.
So, here's a brief rundown on Agatha Harkness's history in the comics.
Founder of New Salem
Agatha's first major chronological appearance occurs when the mutant Firestar is accidentally sent back in time to the Salem Witch trials. Firestar is branded a witch and almost burned at the stake, but rescued by Agatha. However, to Firestar's surprise, Agatha is initially in favour of the burnings, seeing them as ridding the magical community of those who are too weak. At Firestar's urging, Agatha eventually changes her mind, founding the secret community of New Salem as a haven for magic users.
Agatha was the most powerful which in New Salem, eventually rising up to become the community's leader. At some point during her time leading New Salem, Agatha bore a son, Nicholas Scratch. She also offered secret magical help during both the American Revolutionary War, and WW2.
Nanny To Franklin Richards
Eventually, Agatha left New Salem to travel, taking up several jobs tutoring and Nannying children. She briefly retires, but is lured back to the job after Sue Storm and Reed Richards, members of the Fantastic Four, ask her to act as Nanny to their newborn son, Franklin. Agatha, likely sensing Franklin's destiny as a powerful mutant, agrees to the job.
Agatha turned out to be a perfect Nanny for Franklin, helping him learn to control his emerging powers, and even managing to channel his abilities towards defeating Ultron. The Fantastic Four are later able to repay Agatha for all her help with Franklin, by thwarting a plan from her son, Nicholas Scratch, to stage a coup in New Salem.
Mentoring The Scarlet Witch
Perhaps Agatha's most significant relationship in the comics is that which she shares with Wanda Maximoff, the Scarlet Witch. After Wanda discovers that her powers are at least partially rooted in chaos magic, Wanda seeks out Agatha to learn more about it, and as Wanda is such a potentially powerful witch, Agatha is happy to teach her.
Unfortunately, Wanda is unable to save her mentor from a second coup in New Salem, during which Agatha was supposedly burned at the stake. The energies of everyone in New Salem are absorbed by Nicholas Scratch and his daughters, but they cannot control it, and the town is destroyed. Wanda manages to funnel most of the energy away to avoid further destruction. At the urging of Agatha's spirit, Wanda channels some of the energy into herself, resulting in her becoming pregnant with Vision's children.
Agatha eventually returns, having somehow survived her burning, to reveal that Wanda and Vision's twin sons, Tommy and Billy, were actually born from fragments of the demon Mephisto's soul. Rather than attempt to save the twins when they are reabsorbed, Agatha decides the best course of action is to erase the boys from Wanda's memory.
Over the years, Wanda continues to train with Agatha in the use of her chaos magic. However, the decision to erase the twins backfires on Agatha when Wanda recovers portions of her memory. Confronting Agatha, Wanda murders her mentor in a rage upon discovering the truth.
As a Ghost
After her death, Agatha continues to accompany and mentor Wanda as a ghost. She holds very little ill will towards Wanda over her murder, mostly because, following the events of House Of M, Wanda doesn't actually remember it. Agatha occasionally holds it over her, but this is more a dark running joke than true malice.
The most significant appearance of ghost Agatha is in the 2016 Scarlet Witch solo comic. Agatha travels the world alongside Wanda as she attempts to fix a worldwide problem infecting witchcraft. At the end of the story, she is resurrected when Wanda's Mother, Natalya, sacrifices herself to revive the Goddess of Witchcraft.
Visions of the future.
Agatha's next appearance after her resurrection came in The Vision. Appearing midway through the story, she eats a petal from the Wundagore Everbloom, allowing her to see the future. She sees the Avengers dead at the hands of an enraged Vision, and rushes to warn them. However, her warning inadvertently starts the chain of events that almost lead to the future she saw.
Later, she joins the Daughters Of Liberty, a group she had originally been a part of during the American Revolution. This means that Agatha is at least a couple of centuries old.
Agatha All Along!
Now, in WandaVision, Agatha, as played by Kathryn Hahn, seems to have emerged as the villain of the piece. While some are surprised by this development, others not so much.
While Agatha does somewhat care about Wanda in the comics, their relationship is complicated, and not always positive. Agatha has never been above manipulating Wanda to her own ends, and some even theorise that Agatha may have orchestrated the birth of Wanda's twins just so they could be used as weapons against Mephisto, caring little for the pain that this would ultimately cause Wanda. Later, after meeting her mother Natalya for the first time, Wanda learns that Agatha knew who Wanda's Mother was from the moment they met, but had hidden this information from her. While Wanda had learned to accept this kind of behaviour from Agatha by that point, she was still clearly upset.
So, it's not too big of a stretch to cast Agatha as a villain, or at least originate her as one. However, its possible she may be painted as a sympathetic villain once we learn her motives. It's equally possible, even likely, that she is a pawn for a bigger villain down the track.
We'll just have to wait for the final two episodes of WandaVision to learn more of Agatha's plans.