Consider the player as 'pilot' rather than 'hero'. Pilot means machine operator, she who drives the car, manipulates the crane or remote controls the quadrocopter. Her doll is a device, a conduit for action, an extension of their own hand. And as a pilot sometimes this means dangerous or pressured situations. Piloting is therefore immersive.
Sometimes pilots do amazing things like land a plane in the Hudson. This we call 'heroic', but we need to careful about equivocating that kind of hero with a dramatic hero. Dramatic heroes are complex, motivated, a part of the story to which they belong and inextricably bound by the inevitability of its plot. This may be the intent of your narrative, to make the player feel this way, but you don't really get to do that.
You get to present the situation, the storysense, the doll and the rules and encourage them to believe in its reality. Some players will play in the spirit of the game, others will play it literally. They always do they so on their own terms and that's outside your sphere of influence. It's the creative constant of 'self', one of six that bind all games. The player is only ever herself, not the person you might wish her to be.