[Dameria]

Just add a world object variable called "character" and in the beginning of the world, depending on which person you choose, set the character variable to that person. Then, for every place where you do an action with that character, instead of using a specific object like Mana, instead drag the world variable "character" inside there and it will control whatever object that you selected for the character.

Tell me if it works or if you need an example.