Ironheart casually reveals the Marvel villain everyone has been waiting for – and it makes perfect sense

The following contains spoilers for the Ironheart ending.

All eyes are on Doctor Doom right now, but ahead of Robert Downey Jr.'s return in Avengers: Doomsday, Marvel has just debuted another highly anticipated villain in the last place you'd expect.

Following years of speculation, the sixth episode of Ironheart finally introduces Sacha Baron Cohen in the role of Mephisto, a demonic Satan stand-in who wields considerable power in the Marvel universe.

Just one week ahead of launch, Marvel teased this big twist in a breakdown of the Ironheart episode titles that instantly got fans talking. Specifically, the title of the fifth episode, 'Karma's a Glitch,' included the letter 'M' double lined in red, which hinted at the trickster demon and his signature color.

But as fans who have finished Ironheart already know, Mephisto doesn't actually show up until the sixth episode, titled 'The Past is the Past.' Whether that's because the letter 'M' only appears in the fifth title or whether that was just another misdirect from the Prince of Lies hardly matters. Either way, Mephisto is here, and the MCU is going to look very different moving forward.

The devil's in the details

Except, Mephisto has always been here, and we're not just talking about Peter Fonda who played him in 2007's Ghost Rider or Ciaran Hinds who took on the role four years later in the Spirits of Vengeance sequel.

Multiverse aside, the Ironheart finale suggests that Mephisto – or the "Man with Accent," as he's first described by the subtitles – is a cosmic force who has existed for as long as humanity itself. Even Dormammu, Doctor Strange's all-powerful adversary, is just a joke to him: "That ugly pillock isn't fit to clean my glorious arsehole," laughs Mephisto.

"I help people realise their wildest ambitions," he continues, bragging to Ironheart that 14 kings, three popes and even a Beatle (Ringo Starr, to be exact) are just some of the game-changers who have previously benefited from his help. With Riri's "once-in-a-generation mind" and his skills combined, together they can build something "iconic."

But Ironheart isn't impressed. When Mephisto does finally reveal his name to Riri, complete with an ominous choir launched in the background, she simply responds, "Is that supposed to mean something to me?" No, it shouldn't at this point. The pair don't even have history in the comics, let alone this show, but still, that name drop sure does mean a lot to us. After all, the arrival of this trickster demon has been a long time coming.

As far back as WandaVision, fans were convinced Mephisto was the one behind everything that happened in Westview, setting him up to be the MCU's Big Bad when it comes to magic. But after he didn't show up to plague the Scarlet Witch, a surprise name-drop in the sequel Agatha All Along further fuelled those hellish flames, spawning countless fan posts and theories to suggest his arrival was imminent.

Yet Agatha's story came and went with nary a Mephisto in sight. Ongoing rumors that Mephisto might show up in Ironheart instead suddenly felt more tangible when an early trailer revealed that magic would play a prominent role in the show, opening Riri's tech-based story up to the supernatural.

However, it wasn't until the second batch of episodes that Mephisto was actually confirmed. Episode four hinted at his arrival first when Zelma Stanton almost said his name out loud – in reference to an "entity" who "influences" rather than "possesses" – before her mother cut her off.

It's fitting that Mephisto's proper debut on the show would be first hinted at in a magic shop, yet it still comes as a surprise that Ironheart of all places is the story where he would finally be revealed in full.

Created by Stan Lee and John Buscema for the third issue of 'Silver Surfer' back in 1968, Mephisto has since battled a huge array of Marvel heroes, including Ghost Rider, Spider-Man, Doctor Strange, the Scarlet Witch and many, many more. It's probably easier to list the characters he hasn't fought at this point, with Ironheart being one of them.

So why did Marvel decide to introduce such an important supernatural figure in a story that's still quite tech-based (even if some magic has been woven in)?

Tech meets magic

WandaVision felt like a natural fit for Mephisto at first. He's exactly the kind of guy who would toy with Wanda using an illusion like the one we now know Wanda created in Westview. But that was the whole point.

Even with Agatha pulling some strings, the tragedy of the story is that Wanda herself was responsible for everything the town endured due to her battle with grief. To blame her actions on an entity that's indisputably evil like Mephisto would have undercut everything WandaVision stood for.

Of course, Marvel couldn't have anticipated how big the Mephisto rumors would become. Every week, it became a running joke online that Mephisto would be revealed as the true Big Bad. And when that didn't happen, fans suspected the same of Agatha All Along. But introducing Mephisto there would have been very predictable by that point precisely because of those countless fan theories.

And therein lies the genius of this surprise reveal in Ironheart. Leaks and rumors aside, Riri's solo venture really is the last place you'd expect to see Mephisto. It would be like making Dormammu the Big Bad of an Iron Man movie. Except, there's nothing wrong with that, actually.

As much as fans will be quick to criticise Marvel for what feels like a very random decision, they'd be wrong to do so.

Within the source material, a whole host of different tones and vibes can be found in one singular universe, and that's also true of the MCU that it inspires. Magic, science, and everything in between co-exist within these panels and the teams that occupy them.

The Avengers alone count gods, sorcerers, mutants, aliens and scientists among their ranks, both in the comics and on screen too. Yet every solo film or show to date has primarily honed in on the one area that makes sense for the character or characters it spotlights. Aside from She-Hulk, which played around in Marvel's entire sandbox, it's been easy to categorise each story without much blurring to speak of.

By including supernatural beings like Mephisto and The Hood in Ironheart, the show melds two key but often separate parts of the MCU into one cohesive whole, solidifying its world building in ways we've only seen previously in the comics.

It's about time too. If comic book Tony Stark can count a giant magic dragon like Fin Fang Foom among his rogues (and even fight Mephisto himself on occasion), why can't Riri Williams branch out in that same way? In doing so, the writers of Ironheart have also helped further differentiate their hero from Iron Man, setting her on a path that's unlike any we've seen in the MCU to date.

Where Riri's deal with Mephisto will take us remains to be seen, and we might be waiting a while given that Avengers: Doomsday soon approaches.

But it's safe to say that the ramifications of bringing Natalie back from the dead will be rough to say the least. By putting Riri in the devil's debt, Marvel's newest hero might not stay a hero for long, and nothing makes us want a second season more.

All episodes of Ironheart are streaming on Disney Plus now. For more, check out our Ironheart review for our verdict on the show, or see our guide to all the upcoming Marvel movies and shows for everything else the MCU has in store.