While the true identity of Joe Locke’s “Teen” in Agatha All Along remains a mystery, a wild new MCU theory might have provided the most unexpected suggestion. Joe Locke made his MCU debut as a fan and fast friend to Kathryn Hahn’s Agatha Harkness, but it’s still unclear who the Heartstopper star is actually playing in the MCU. Dubbed “Teen” by Agatha, because he’s 16-years-old, he has joined the new Westview coven on their journey down the Witches’ Road, but each new episode of Agatha All Along raises new questions.

There have been many theories about who Joe Locke could be playing in the MCU, with the most popular, and perhaps most likely, outcome naming him as Billy Kaplan, a.k.a. Wiccan, the reincarnated son of the Scarlet Witch. While promotional material for Agatha All Along seems to have already confirmed this, there has been no mention of this in the series, so the truth could be vastly different. A new theory suggests that Joe Locke might not be playing a human character at all, but could, in fact, be the MCU’s Book of the Damned.

Joe Locke’s “Teen” Could Be The MCU’s Darkhold As A Human

Agatha All Along Has Developed The Darkhold A Great Deal

Marvel Studios first introduced the Darkhold to the MCU in 2021’s WandaVision, with the Book of Sins being in the possession of Agatha Harkness. Wanda Maximoff stole the Darkhold at the end of WandaVision, allowing her to dream-walk in 2022’s Doctor Strange in the Multiverse of Madness in search of her children from another reality. Multiverse of Madness ended with the Scarlet Witch sacrificing herself, and destroying every copy of the Darkhold across the multiverse, but she may have spared one special version of the book.

Darkhold’s MCU Appearance
Year
User

WandaVision
2021
Agatha Harkness & Scarlet Witch

Doctor Strange in the Multiverse of Madness
2022
Scarlet Witch, Doctor Strange, Earth-838’s Doctor Strange, Sinister Strange

Agatha All Along
2024
Agatha Harkness

The Darkhold plays an important role in Agatha All Along, and is continuing to be developed as the series progresses. Agatha All Along episode 3, “Through Many Miles of Tricks and Trials,” hinted at the idea that Agatha Harkness may have traded her son, Nicholas Scratch, to acquire the Darkhold. This rumor is supported by the fact that Agatha sees the Darkhold in a crib in her hallucination caused by the Alewife’s Revenge. It isn’t too much of a stretch to suggest that the Darkhold may be anthropomorphized in Agatha All Along.

Agatha All Along’s Corpse’s Toe Tag Hints At The Body Not Being Human At All

The Identity Of Agnes Of Westview’s Corpse Hasn’t Been Revealed

The first half of Agatha All Along episode 1, “Seekest Thou the Road,” featured Agatha Harkness in her Agnes O’Connor guise, inhabiting a true crime-style world, inspired by Mare of Easttown. As a rogue detective, Agnes was brought in to investigate a corpse found in the woods, who the audience is led to believe is that of Wanda Maximoff. This makes sense, given the Scarlet Witch’s apparent death in Doctor Strange in the Multiverse of Madness, but there are hints this could be someone, or something, else entirely.

Doubt was cast on the body in the woods being a woman, and attention was drawn to “Teen’s” blackened fingers during his interrogation, perhaps suggesting they could have been one-and-the-same. The fact that the Darkhold’s library card appears as a toe-tag on the body in the morgue is perhaps the most overt clue that this body may actually be the Darkhold itself. It’s only through Agnes’ unreliable narration that the body becomes a woman with red hair, reminiscent of the Scarlet Witch. Prior to that, it could very easily be the Darkhold in human form.

“Teen” Has Already Displayed A Huge Amount Of Power In Agatha All Along

“Teen” Helped Agatha Harkness Break Free Of The Scarlet Witch’s Spell

During his interrogation at the hands of Agnes O’Connor, “Teen” breaks out into a little bit of Latin, which he later suggests helped loosen the grip of the Scarlet Witch’s spell. Agatha was later able to strip herself of her Agnes disguises, many of which audiences will remember from WandaVision, eventually ending up naked in her own living room, completely free of the spell. The fact that “Teen” was able to help break the Scarlet Witch’s spell is incredibly impressive, and certainly not something just a student of basic magic would be able to do.

A different version of the Darkhold was seen in Marvel Television’s Agents of SHIELD , and reappeared in Runaways , but these shows haven’t been confirmed to be canon to the MCU’s main continuity, and this Darkhold looked very different to the MCU’s current iteration.

While some have suggested that this could support the theory of “Teen” being related to the Scarlet Witch, perhaps making it easier to break her spell, the level of power needed to pull off this feat is incomprehensible. The Scarlet Witch is one of the most powerful beings in the universe, so it could be unlikely even her own son would be able to crack her spell. This may support the idea that Joe Locke is, in fact, playing a human iteration of the Darkhold, as this book has more power than the Scarlet Witch.

How Teen Can Be Both The Darkhold & Billy Kaplan In Agatha All Along

The Scarlet Witch May Have Brought Her Children To Life Upon Her Sacrifice

In an effort to avoid the complicated story of Billy Kaplan and Tommy Shepherd from Marvel Comics, Marvel Studios may have simplified their origins. Upon her death in Doctor Strange in the Multiverse of Madness, the Scarlet Witch may have used her last bit of magic to reincarnate her sons, Billy and Tommy Maximoff, in the bodies of two teenagers who may have met their own tragic ends. However, she also used this moment to destroy every copy of the Darkhold, so it’s very possible these spells could have been combined.

This may have inadvertently gifted Billy Kaplan and Tommy Shepherd, who hasn’t yet been seen in the MCU, but is the reincarnated version of Tommy Maximoff’s Speed, the abilities of the Darkhold. This could have fueled “Teen’s” obsession with witchcraft and Agatha Harkness, especially since the book was in her possession for so long before WandaVision. Agatha All Along still needs to address the mystery of its Agnes of Westview opening, and revealing “Teen” to actually be the Darkhold – the thing Agatha wants so much – would be game-changing.