WARNING: The following contains minor spoilers for WandaVision Episode 7, "Breaking the Fourth Wall," now streaming on Disney+.
The Scarlet Witch has faced some pivotal challenges in her MCU history. Two of the biggest events in Wanda's life have been meeting Agatha Harkness and her incident in Lagos, Nigeria.
In the comics, one relatively minor villain has a connection to both Agatha and Lagos.
This villain, The Emerald Warlock, was introduced in Uncanny Avengers Annual #1, by James Robinson, Marc Laming and Jose Giles. Dian, The Emerald Warlock, has assumed several aliases over the years. During World War II, Dian was known as Declan Dane. At this point in time, The Emerald Warlock was recruited with a group of other magic-powered individuals for the Department of the Uncanny.
Dian worked alongside Ghost Dancer and Agatha Harkness to stop magic-based Nazis such as Hilda von Hate. The Department of the Uncanny worked with Captain America himself to stop Hilda and her zombie army. Decades later, Hilda's zombie curse returned. The Emerald Warlock and Ghost Dancer were forced to confront Hilda's curse alongside Steve Rogers and the Avengers Unity Squad.
It turned out that a hate demon, which possessed Hilda decades earlier, was responsible for the resurgent zombie curse. After Dian absorbed this demon into himself, he murdered Ghost Dancer, revealing his truly evil nature. The Emerald Warlock decided to set his sights on The Scarlet Witch from this point forward.
In The Scarlet Witch #3, by Robinson, Steve Dillon and Chris Visions, The Emerald Warlock was revealed as the mastermind behind recent events in Wanda's life. Dian attacked Wanda by summoning demons, turning Man-Bull into a minotaur and attacking her with an army of wicked spirits.
Along the way, The Emerald Warlock traveled to Lagos, a major landmark for Wanda in the MCU. Dian went to Lagos so he could wipe out the final descendants of Tuatha De Danaan, mages who prevented him from attacking Ireland centuries earlier. Although Wanda wasn't present for Dian's trip to Lagos, in both this instance and in Captain America: Civil War, major acts of violence occurred.
After Dian's violent spree, The Scarlet Witch confronted him on Witches' road, where he was defeated. The Emerald Warlock's most recent appearance was in The Scarlet Witch #15, by Robinson and Vanesa Del Ray. In this issue, Dian attempted to steal the power of a young boy who was descended from a powerful sorcerer. Fortunately, Wanda stopped Dian and exorcised him from the boy.
Considering how minor a role The Emerald Warlock has played in the comics overall, it's fascinating how well-connected he is to The Scarlet Witch's MCU history. It's true that Dian's appearance in Lagos is probably just a coincidence, but still, the fact that an enemy of The Scarlet Witch committed murder in the same location as one of Wanda's biggest MCU moments is quite a large coincidence. Both instances were horrific, and both were related to The Scarlet Witch on some level.
An even bigger coincidence is Dian's connection to Agatha Harkness, who plays a massive role in WandaVision. The Emerald Warlock not only worked with Agatha back in World War II, but Agatha's spirit guided Wanda in her fight against Dian. Looking at Agatha's major role in the MCU, The Emerald Warlock is a bigger player than he first appeared to be.
Dian has ties to both Agatha and Lagos, while also being The Scarlet Witch's self-proclaimed "archenemy." With all of these connections to The Scarlet Witch both in and out of comics, it's funny that The Emerald Warlock is only a minor villain. Perhaps in the future, The Emerald Warlock could make his MCU debut.