To endow the synthetic characters with autonomous behaviors interests several fields of researchers, especially the experts of computer graphics. In this paper, we propose a believable brain architecture to allow the synthetic character to achieve high level of autonomy. There are three new capabilities. Firstly, this architecture is not a simple stimulation-action model, but adds a layer between stimulation and action called agency that plays a role of extraction and synthesis. Secondly, hierarchy Finite State Machines (FSMs) and fuzzy logic techniques are embedded into the synthetic character’s brain. Finally, the ability to integrate the emotion expression model into the brain architecture allows the synthetic characters to express their sensibilities such as happy, angry, sorry, etc., which can inspire the users’ passion and fuse them into the virtual world.