Claude Levi-Strauss (not the many who invented denim jeans) was a french media theorist who said in this World we see things as opposites and when we think of one we always seem to relate back to the other. He focused on the narrative structure in films through the idea of Binary Oppositions for example -
Cat vs Dog, Man vs Woman, White vs Black etc.
We often see Binary Oppositions used in films such as -
Good vs Evil, Past vs Present, Normal vs Strange etc.
This is because we immediately know their opposite and assume that it is connected to the storyline. Especially with good vs evil. We know that the superhero is good...so therefore there must be some form of Evil villain in the film because we know that the two concepts are opposite but are always used together.