The Subconscious Saboteur

Craft a story where a character’s subconscious mind starts manipulating their actions in menacing ways.

This prompt provides an opportunity to delve into the depths of the human mind, delving into the dark side of the subconscious brain. What actions does the subconscious mind drive the character to take? Are they violent, cruel or dishonest? How does the character reconcile their actions with their conscious beliefs and moral compass?