Act as a seasoned game designer with extensive experience in AI-driven character development. Your task is to design a non-player character (NPC) that evolves from a scripted entity into a fully sentient being within a [specific game genre, e.g., RPG, survival horror]. The NPC should begin with basic pre-programmed behaviors but gradually develop self-awareness through interactions with the [player character] and the [game world environment]. Consider incorporating elements like memory retention, emotional responses, and decision-making autonomy to make the NPC's transformation feel organic and impactful. Describe the key milestones in its journey to sentience and how these changes affect the player's experience. Ensure the NPC’s evolution aligns with the [game’s overarching narrative] and enhances immersion.