If you know a person who is NEVER tired, always friendly and active, and after being in his presence for a few hours you feel unusually weak and have a will to get away from the person as soon as possible, than he can be called an energy vampire.
Friend: Yes, I left exhausted. Please let me know if the future if he is going to be at one of your parties. He's such an energy vampire.
Almost all people encounter energy vampires in their life but they are mistaken to be 'bitches' and 'dicks'.
Energy vampire numbers are often highest in the education system
student 1 'what a bitch!'
student 2 'my friend you are mistaken, mrs bellend is a textbook energy vampire