"'' he sliced them down the middle ? '' '' yes and no . there was a byproduct of the magic i do n't think my grandfather was prepared for . when he combined a human and an animal , he expected his magic would create only one being . instead , it made two of them . one person who held the heart of a human , and a separate creature whose heart was that of the _ ..." What is the word in the blank space (_)? The answer is
animal