Spoilers for Doctor Strange follow.
Over the weekend, Doctor Strange opened in theaters and audiences not only met the Sorcerer Surpreme-to-be but also two of foes. Kaecilius appeared to be the focal villain of the film but, as it turned out, Dormammu was pulling the strings behind the scenes all along.
According to Marvel Studios president Kevin Feige, the original plans for Doctor Strange did not include Dormammu as the main villain. Instead, the plans involved another Strange villain: Nightmare.
“Kevin [Feige] made a very cogent case,” says Derrickson. “The trouble with starting with Nightmare is getting across the idea of the Dream Dimension as another dimension. The movie was challenging enough. It's already an exposition-heavy movie... Dormammu made the most sense. And he is the most present villain in the comics.”
Nightmare, the controller of the Nightmare Realm and Dream Dimension, has encountered Doctor Strange on several occasions. Dormammu, however, has been a long running villain of the series but may also have been selected for larger reasons than Feige is leading on.
As ComicBook.com's Kofi Outlaw points out, Dormammu may turn out to be the Galactus of Marvel's Cinematic Universe. With rights to the world devourer sitting with 20th Century Fox, the on-screen world will be in need of building towards a new powerful villain once Thanos' story plays out in the Avengers: Infinity War movies.
As Outlaw points out, The Ancient One refers to Dormammu as a "devourer of worlds," he bestows power upon Kaecilius, and cannot be beaten - only bargained with.
Nightmare would not have been a gamechanger for Doctor Strange as the closing sequences could have been similarly manufactured with a villain swap. However, his dimension would have been a gamechanger while Kaecilius and his powers would have likely been altered, as well.
It is entirely possible Nightmare was swapped for Dormammu in favor of building a new big bad purple villain for the Marvel Cinematic Universe. Wherever we see Strange in the future, we are eligible to see Dormammu - not because the characters are tied together in story, but because Benedict Cumberbatch plays both. The actor performed the voice and motion capture sequences for Dormammu which were seen at the end of the film.
As for why Mordo did not fall into villainy prior to Doctor Strange's post-credits scene, director Scott Derrickson says he has other plans for the character.
"I didn't want to do what the comics did and start off with Mordo just being and arch nemesis and a bad guy straight from the beginning," Derrickson told ComicBook.com. "I think with all so called villains, with all antagonists in any movie, you are only as invested in them as you are in their point of view and Mordo has a good strong point of view in this movie and the same is true of Mads Mikkelson's character. They're both men of idea, men of principles, men of beliefs and those are the kind of antagonists I enjoy watching, so we tried to make a movie with those kind of antagonists."
Doctor Strange is now playing in theaters.