On Twitter, Hideo Kojima shared his musings about creating a new character and what kinds of considerations go into the process.
When creating brand new character, I think of every detail. Name, Sex, Race, Looks, Personal history, Future, Habit, Outfit. The role of the story/ on the theme. The balance with other characters. I consider the movement, the evolution in the game, and how he comes in/out. And recently, I also consider if the character is attracted by Cos-Players. The charaters that the Cos-Player can think it’s easy or hard but challenging or it limits the target, or it shines Cos-Play. The character who let Cos-Player deformed/arranged a bit. Also I consider the balance for the group of Cos-Players.
In short, a lot of factors are being considered when creating a new character from scratch. Maybe Kojima is in the middle of that process right now for his new game.