How to Write a Doppelganger
To write an effective doppelganger, you first need to have a well-established character. This works best with the main character, or perhaps a love interest or trusted ally. One way or another, readers need to feel familiar with the character that’s being doubled. That way the contrast between the two characters will stand out more clearly.
You then need to have some kind of device that creates the double. In realistic fiction, the doppelganger might be a literal twin, perhaps one separated at birth. However, in science fiction and fantasy there are many other ways to create doppelgangers, such as enchanted mirrors, cloning, and parallel universes.
Although most doppelgangers are evil, this isn’t the only way to write them. You can also generate some humor by making the doppelganger goofy or stupid, like Bizarro Superman in some of the DC Comics cartoons.
It’s extremely common to give evil twins beards, whereas their regular counterparts are clean-shaven. This was true, for example, of “Evil Cartman” from South Park, and many characters from the Star Trek Mirror Universe. This trope may go back as far as the Bible, where Jacob’s evil twin Esau is described as “hairy,” while Jacob himself is “smooth.”
When to use Doppelganger
The doppelganger is purely for use in fiction. Formal essays have no use for this device. Within fiction, though, doppelgangers are generally used more in science fiction, horror, and fantasy genres. The concept of an evil twin, for example, is not very realistic, and so it doesn’t fit very well in realistic fiction.
It’s also important to be aware of the clichéd nature of doppelgangers in many genres. Again, the evil twin is a good example – this story is so common that it may not read as very creative. In order to bring more creativity and originality into your doppelganger story, try to be subtle in your use of the device. For example, you might make the doppelganger a shadowy, mysterious figure who is always just out of reach of the reader’s understanding. Or, you might try telling the story from the doppelganger’s perspective, thus raising the question of who is the original and who is the “double.”