To turn a VTuber model into an AI model, keep the avatar (Live2D/3D) for visuals, then connect it to an AI chatbot or voice AI by training/customizing a language model with your character’s personality, responses, and lore, plus add text-to-speech and speech recognition for voice interaction. Tools like Unity, VTube Studio, or VRM apps can sync the avatar with the AI brain for real-time conversations.