Two concepts for the Inner Voice. Ideally, the Voice does not have a phsyical presence, rather they are your subconcious. The concept was to make the character appear ghost-like as if they are the soul to the main character in the game.
FIERO is a world covered by Metus--a thick dark fog that is a representation of Anxiety. The goal of the game is to go through a series of challenges and puzzles that will make the player encounter their fears. As they progress, the fog will clear and open a new path.