Sam is a person.
What kind of person is Sam? What does Sam believe? How does Sam react to any given situation? Who does Sam love? What does Sam love?
All of the above questions are answered by you the voices in Sam's head.
As GM I will give prompts/decisions that Sam faces. You as the players will be the voices in Sam's head making the decisions, debating your morals, defining who Sam is. Feel free to not only make decisons for Sam but also define Sam's history and life. The player completely define Sam past, present, and future.
Once GM makes a prompt the voices in Sam's head can debate. If you feel like you know the best course of action for Sam you can make Sam take action. Once Sam has taken an action other voices (players) can question Sam's actions or agree with them while they await the GM's reaction post. Reaction posts will define how the world/NPCs reacted to Sam's actions.
Sam's voices do not have to agree but once an action is taken it can not be taken back. Simple actions like walking across the room, eating, or sitting down can happen without a GM reaction post but complex interactions like speaking to a person or going across town will require a GM reaction post to progress.
Post actions taken in italics and anything Sam says outloud in quotations.