Variety is the spice of life and writing. We all choose a certain genre, usually, to write in. It may be as general as fiction or non-fiction, but usually we break out into specific genres, like historical, science fiction or science fact, biography, you see what I mean.
Within your story you need variety in your characters. You can make them mirror image of each other meaning they can act alike, but their reasons are opposite. When one is acting from the right the other is from the left. Or you can make them quite alike and present them with different situations and see what they do to handle the action.
You will want to use variety in the scene settings. Move the characters from the city to the country. Or from room to room, whatever fits the action and here, you can also set the scene in an unusual setting. Maybe a love scene in a garage or a dinner in a canoe.
That may all sound a bit far-fetched, but if you put your characters in unusual situations, they will act in unusual manners.
Remember, variety is the spice of life and writing.