Outside of writing fiction, I play Larp. For those unfamiliar with it, it’s a form of improvisational theatre without an audience. If you’re curious, more information can be found here, for instance: https://en.wikipedia.org/wiki/Live_action_role-playing_game. While my short story and novel writing was slowing down, I did write several characters for Larp, and some plot for Larp, for other people to encounter. It got me musing about the similarities and differences between both kinds of writing.
With both kinds of writing, I first write the backstory of the character(or imagine and fail to write down, sometimes, with short stories). How did the character end up there? What does the audience need to know about the character, and how does the character’s background influence their decisions. I try to make the character as realistic and vibrant as possible, without making the background so complex I can no longer work with it, either in the game or in the story.
Also, with both kinds of writing, I try to create as interesting a setup as I can. To put the starting condition so, that the characters have something interesting to deal with.
Which brings me to the major difference between the two. Players happen. So from the moment you send the setup into the game-world, how the players interact with it, solve the problem, is out of your hands. All you can do is hand them tools, if necessary, or try to put them on a path by what information you release when to them. Even still, if you come up with 5 or 6 possible solutions or courses of action, they will present you with a 7th. If you’re writing the entire story, you can steer your characters to the most interesting outcomes, determine exactly when what reaches them, and if the outcome is unsatisfactory, you can go back and tweak until it works better for you. You write the continuation of the story of the character you’ve created, and control all the aspects of the story. You are chained by your own imagination, though, if you are inventing all of it.
Thus, both have a lot in common, while they still differ significantly. They have their own challenges, but also a lot of potential to build synergy, the one helping you become more imaginative in the other. I am enjoying how doing both is expanding my horizons very much.