WARNING: The following contains spoilers for Marvel's WandaVision Episode 3, "Now in Color," now streaming on Disney+.

There is plenty of mystery at the heart of Marvel's WandaVision. In the Disney+ series, Wanda Maximoff and Vision are living a seemingly idyllic life in a reality based on various eras of television sitcoms, but something clearly isn't right. From the start, it's been clear that there is more happening behind the scenes of Westview, and fans have their own theories about the villain that may be responsible.

Star Paul Bettany has added more fuel to the fire by dropping an intriguing tease, revealing that a mystery character will appear on the show. But while some may take the actor's comments as confirmation that Mephisto will appear in WandaVision, it's just as likely Bettany is talking about Doctor Strange.

RELATED: WandaVision's Third Commercial May Hide An Agents Of SHIELD Reference

WandaVision - Paul Bettany as Vision

In a recent interview with Lights, Camera, Pod, Paul Bettany teased the appearance of a surprise character on the series.  "You know, so many things get leaked, and people find out about certain things, but there's this thing that's been kept completely under wraps," he said. "I work with this actor that I have always wanted to work with, and we have fireworks together, and the scenes are great, and I think people will be really excited."

After three episodes, there are several prevailing theories about who the main villain of WandaVision really is. Right now, fans are convinced that Kathryn Hahn's Agnes is actually the villainous Marvel witch Agatha Harkness. From what we have seen of the mysterious character in the series' first three episodes, as well as in WandaVision's trailers, it seems all but clear Agnes is a villain, and that she will eventually clash with Scarlet Witch and Vision.

Since Bettany is talking about working with a male actor, others might take this as almost a confirmation that the Marvel Universe's version of the Devil, Mephisto, will appear on the show. The first episodes of WandaVision dropped several clues that the Devil could be involved in the series, and many fans are convinced he is the real villain of the Disney+ series. However, it's also important to note that Bettany never actually specifies that he's facing off with a villain. In the larger context of the interview, Bettany explains that, by the end of the series, fans will see the MCU in a new light. When using that as context, it's possible Bettany is actually talking about Benedict Cumberbatch's Doctor Strange.

RELATED: WandaVision: Sparky The Robot Dog's Tragic Life & Death (& Resurrection)

After all, it was already confirmed that WandaVision will lead directly into Doctor Strange in the Multiverse of Madness, in which Elizabeth Olsen will reprise her role as Wanda Maximoff. Since there is a connection between the series and the upcoming Doctor Strange sequel, it's likely the Sorcerer Supreme could appear near the end of the series to bridge the gap between the two.

Now sure, Bettany said that the actor is someone with whom he had always wanted to work with, and he and Cumberbatch previously starred in the 2009 film Creation. However, that was a long time ago, and perhaps Bettany was specifically talking about working with this actor in the MCU since, although Vision and Doctor Strange both appeared in Avengers: Infinity War, the two characters never actually met.

If Doctor Strange visits Westview, perhaps in order to help Wanda, then he would certainly face Vision. The fireworks between Vision and Doctor Strange could refer to the Sorcerer Supreme trying to dismantle Scarlet Witch's reality, and Vision trying to stop him. There are plenty of possibilities, but at this point, it seems all the more likely that fans will see Doctor Strange in WandaVision.

KEEP READING: The CBR WandaVision Hub For News, Easter Eggs, Reviews, Rumors, Theories And MORE