“Black Heart”: Marvel Just Dropped Another Mephisto Reference & Sparked The Best New MCU Theory

Warning: This article contains spoilers for Agatha All Along episode 1, “Seekest Thou the Road,” and episode 2, “Circle Sewn with Fate/Unlock Thy Hidden Gate”

An important character related to Mephisto in Marvel Comics might have just been referenced in Marvel Television’s Agatha All Along, spurring a huge and believable new MCU theory. The first two episodes of Agatha All Along have finally premiered on Disney+, and Kathryn Hahn’s Agatha Harkness has already been broken free of the Scarlet Witch’s spell, and has gathered a new coven of exciting witches and set out on the Witches’ Road in an effort to retrieve her power. If that wasn’t enough, the double-premiere may have also provided the MCU’s most recent Mephisto tease.

Based on the Faust demon Mephistopheles, Mephisto is one of Marvel Comics’ most notable, recognized and powerful supervillains. This prominence makes his debut in the MCU inevitable, but Mephisto has now been heavily rumored to be making his grand entrance for several years, with hints of his existence being featured in WandaVision, Loki and She-Hulk: Attorney at Law, among others. Agatha All Along may have just teased Mephisto yet again, as there were several mentions of a “black heart,” which could, in fact, be referring to Marvel Comics’ Blackheart.

Who Is Blackheart & How Does He Relate To Mephisto?

Blackheart Is Mephisto’s Son In Marvel Comics

Blackheart is a terrifying character in Marvel Comics, created by Ann Nocenti and John Romita Jr., and first seen in 1989’s Daredevil #270. Most commonly depicted as a dark and demonic adversary to Ghost Rider, Blackheart has crossed paths with a number of other heroes, including Daredevil, Spider-Man, Wolverine, Wonder Man and Sam Wilson, among others. Blackheart is remarkably powerful, with a wealth of supernatural abilities, and, interestingly, he is also depicted as Mephisto’s son, as the more notable demon used magic to create Blackheart.

After centuries of murder in the town of Christ’s Crown, New York, Mephisto used the accumulated evil energies in the town to forge Blackheart. Mephisto trains his son in the art of evil, but Blackheart becomes fascinated with humanity’s free will, and soon turns his back on Mephisto, beginning an age-old feud between the pair. In his war against Mephisto, Blackheart carries out some heinous acts, and tries to lure various heroes to join his cause. Blackheart later becomes more of a conventional villain, taking Mephisto’s place as a ruler of Hell.

Agatha All Along’s “Black Heart” Moment Explained

Agatha All Along Made A Big Deal Of Rio Vidal’s Black Heart

Agatha All Along first two episodes mentioned a “black heart” on several occasions. Most notably, Patti LuPone’s Lilia Calderu notes in episode 2 that the fifth name she jotted down as prospective members of the new coven wasn’t a name at all, but a drawing of a black heart, with Agatha hilariously suggests is simply because she was using a black pen. While Agatha tries to explain that this must mean Debra Jo Rupp’s Mrs. Hart, a.k.a. Sharon Davies, harking back to WandaVision’s premiere, Calderu’s black heart drawing actually refers to Aubrey Plaza’s Rio Vidal.

During the fight between Agatha Harkness and Rio Vidal at the end of Agatha All Along episode 1, Vidal mentions that she does indeed have a heart, and that it is black and beats for Agatha. Lilia Calderu was suggesting that Vidal, a Green Witch, would be necessary for the coven to access and survive the Witches’ Road. Vidal’s own declaration that she has a “black heart,” however, has spurred a major new theory that she could, in fact, be Marvel Studios’ interpretation of Mephisto’s child from Marvel Comics.

Marvel Fans Think Agatha Is Setting Up Rio Vidal As Mephisto’s Daughter

Rio Vidal’s Backstory Hasn’t Yet Been Explained

The repetitive mention of a black heart and its connection to Rio Vidal in Agatha All Along’s double-premiere has caused many to theorize that Aubrey Plaza’s MCU character could be a depiction of Blackheart from the comics (via X). This would not be the first time that Marvel Studios has gender-swapped characters from Marvel Comics, and this would be an incredible way to tease Mephisto’s much anticipated debut. Nothing is yet known about Rio Vidal’s backstory or her history with Agatha Harkness, but the upcoming episodes of Agatha All Along could finally bring Mephisto, perhaps Vidal’s father, into the MCU.

New episodes of Agatha All Along release every Wednesday at 6pm PT / 9pm ET.

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