Marvel has spent the past decade getting us to Avengers: Infinity War for the epic battle with Thanos. Most of that time has been spent having our characters fight their evil counterparts: villains who match—or mirror—their heroes. This isn’t just an MCU trope. It’s one of the oldest tricks in the book.
Good and evil have long been treated like two sides of the same whole, and sometimes that’s portrayed literally. In Zoroastrianism, the oldest-known religion, good and evil were sometimes portrayed as twins—Ormuzd was the light, and Ahriman was the darkness. For Babylonians, demons were physical manifestations of their gods’ nastier personality traits. Then, of course, you had the Judeo-Christian Bible, which is chock full of these duos: God and Satan. Cain and Abel. And the Antichrist, who’s basically as “on the nose” as you can get. He’s literally the anti of Jesus.
When it comes to the evil counterpart, one of the most popular predecessors is the doppelgänger. These beings have gone by several names in folklore, like changeling, ka, and yes, even fetch (like from Mean Girls). A doppelgänger, which translates to “double goer,” is basically a double of a living person. It’s sometimes supernatural, sometimes not, but it’s often viewed as a harbinger of doom. Which is funny, considering the actual word “doppelgänger” was created by Jean Paul for his 1796 German romantic comedy Siebenkäs, and it was used to describe two food courses being served at the same time. The real term he came up with was doppeltgänger, but clearly, that didn’t stick.
Other examples of the doppelgänger in fiction include E.T.A. Hoffman’s 1815 story The Devil’s Elixirs, about a monk haunted by his doppelgänger, who was actually a man the monk had tried to murder in the past. A few decades later, Edgar Allan Poe’s Gothic tale William Wilson spooked us with a creepy double, and Hans Christian Andersen’s The Shadow was about a man’s shadow that frees itself and slowly takes over the man’s life. Then, of course, there’s Dr. Jekyll and Mr. Hyde, one of the most famous stories of an evil doppelgänger, this one created through science.
These aren’t just fairy tales. There are also real stories of people claiming to know their evil counterparts, though most of them don’t end well. The most famous example is Abraham Lincoln. An early biography describes a moment where just after Lincoln was elected president for the first time, he looked in a mirror and saw two faces—one paler than the other. His wife told him it was a sign he would get a second term, but he wouldn’t live through it. From Carl Sandburg’s Abraham Lincoln: The Prairie Years, adapted from an 1895 biography by Noah Brooks:
It bothered him; he got up; the illusion vanished; but when he lay down again there in the glass again were two faces, one paler than the other. He got up again, mixed in the election excitement, forgot about it; but it came back, and haunted him. He told his wife about it; she worried too.
A few days later he tried it once more and the illusion of the two faces again registered to his eyes. But that was the last; the ghost since then wouldn’t come back, he told his wife, who said it was a sign he would be elected to a second term, and the death pallor of one face meant he wouldn’t live through his second term.
These stories have been popular over the centuries—up through Avengers: Infinity War—because they explore human duality and give characters a way to interact with the more, well, evil parts of themselves. While they do show how good and evil aren’t that different, and we’re all capable of both, the bigger reason behind the evil counterpart has to do with the characters themselves. Specifically, their emotional journeys. Everybody has flaws—even the Avengers. And it’s not always easy for characters like these to see, grasp, or confront their flaws while still giving us a fun action film. So the easy solution is to give those flaws a different face.
“A double can stand-in to personify a character’s dark side,” researcher Tom Little told io9. “Remember Superman’s crisis of character in Superman III? Recklessly drunk and bitter, a burdened hero splits himself into two personas, one hateful and the other still keen on truth, justice, and the American way. The two duke it out in a junkyard brawl, and the morally upright Clark Kent eventually wins out, because that’s who Superman really is.”
This type of enemy lets heroes not only fight a bad guy, presumably with lots of big explosions, but also discover something about themselves. It’s an internal battle, using an external foe.