Alice was rather perplexed by the professor's second question. "Hmm.. What makes a dark creature differ from a NON-dark creature?" .. She was having a bit of difficulty coming up with an answer, and she thought maybe it would be best to answer with what exactly came to her head first.. "Er well I would think that a dark creature, such as a demon or a dementor would be used ultimately to inflict harm, so.. A dark creature would be something that feeds off of harm that it inflicts on people, or anything of the sort."