There seem to have been a lot of threads lately along the lines of 'is it okay for vampires to do this?', or 'can this fantastical creature be like this?'. I just want to put it out there that if you are writing a fantasy story then the whole point is that you can do with it whatever you please! Even if your creature is inspired by an existing mythological creature it doesn't mean you have to stick to the 'rules' about it. You could even use your creative juices and make something up from scratch - why not, all the exisiting mythological creatures were made up by someone once. Always remember that it's YOUR story, so you make the rules!