Denny is not a chocolate bar, but in fact a ghost possessing a chocolate bar. Being possessed gave the chocolate bar the ability to walk and talk in Denny’s voice.
DENNY IS INVINCIBLE, MEANING HE CAN’T DIE OR BE DESTROYED. HE CAN STILL BE DAMAGED, SUCH AS HAVING PARTS OF HIM BITTEN OFF OR MELTED OFF. PLUS, HE’S EXTREMELY WEAK IN TERMS OF ATTACKS.