Superman would be dreadfully boring without Kryptonite. Weaknesses add dimension. We also say that they add “dimension” to your character.
Dimensions come in various forms:
One dimensional characters are characters limited by their looks….i.e. physical appearances.
Two dimensional characters extend their persona to the story. It’s what we use to determine what makes villains or heroes, etc.
Three dimensional characters have a side of them that we do not normally see at the surface but which surfaces at some point in the story. Usually this side of the character is opposite to their two dimension persona. i.e. a bad person may demonstrate some good attributes. An evil person may demonstrate kindness.
A few years ago I had been developing a villain for a story. When I was done I scrapped the project because it didn’t seem to work. It wasn’t after several years when I learned about multi-dimensional characters and the value it adds to character development. My mistake was making the villain absolutely deplorable without adding one or more attributes showing that he was also human. If I were to recast this villain I would keep all the stuff that makes him terrible but I would also show him in a scene or two as being kind. Perhaps he helps a blind man crosses the road?
Here are some examples from literature to demonstrate the point:
In the Joker there’s a scene where Arthur (Joker) has a visit by Randall and fellow ex-colleague Gary. Arthur murders Randall but leaves Gary unharmed for treating him well in the past. This shows compassion on Arthur’s part but it also leaves us with a feeling that there is some humanity left.
Rosemary’s Baby (1968)
Rosemary is weak both mentally and physically – but she has sudden courageous bursts challenging the Luciferians.