 Harry later speculates that he was able to willingly do this because it was Harry who gave him his name.Although Bob has no physical features of his own, appearing as a sort of orange cloud of light, he can create expressions within the skull, appearing as eyes of orange dots of light, which can roll and narrow and adjust to mimic human expressions.He can use the skull itself to express emotions, such as letting the jaw drop open in surprise (real or fake), or turning to bang the forehead against the wall in frustration.