I'm currently writing a story in which our protagonist is trapped in a labyrinth of sorts. The twist here is that she is the monster within this maze yet she does not realize it as she has no memory of any recent events and simply woke up there. Over the course of this short story, she learns of what she is and slowly regains her memories. But just as quickly as she regains her memories, they begin to fade as she is slowly devolving into a mindless beast. What would you say is the best way to approach my protagonist's thoughts and emotions throughout this?
I think once you settle on how this transformation takes place that you’ll understand how to relate it in your story. Is the transformation outward to inward — they take on appearance of monster and slowly their mind and values are monstery? Or do they wrestle with in inner transformation the takes their mind first and then transforms the body?
And is it continuous? Or can they focus on the mission, or remember their true love and gain respite or ground from the transformation?
Once you have that arc of transformation solidly understood, then you’ll see how to represent it in terms of the characters dialog, interior thoughts, emotions and actions