He apparently is not afraid of Lucci and is very loyal to him, as he stays close to his master even in dangerous situations like the Buster Call. Lucci would have had to express some emotions to blend in with citizens while undercover, but Hattori did this for him as his ventriloquist dummy; this allowed Lucci to be somewhat sociable while at the same time remain emotionless. When Lucci is not fighting, Hattori is usually perched on his master's right shoulder.