She looks at you with interest as you walk back with the chalice; an interest that increases as you cut yourself and allow your blood to drip into the cup. Her eyes grow larger and she runs her tongue around her lips in anticipation. She takes the goblet and sniffs deeply of the warm blood you are offering her, almost as how a wine connoisseur would treat a glass of fine wine. Carefully, the vampire lifts the chalice and sips at the blood in it, making a sound of intense pleasure as she drinks. When she lowers the cup, there is no sign of the blood in it or on her lips, but there is an odd look on her face. "My very existence is forbidden and my kind are hunted ruthlessly in every corner of the globe, yet you have accepted me into your life and your bed without any apparent qualms. You have freely offered your most precious physical asset, your blood, to me without fear or prejudice. History, legends, and rumors all conspire to paint my kind in the worst possible light but you look at me differently than others of your kind. You would almost certainly be considered insane for befriending me."
She motions for you to give her the knife and cuts the back of her own hand, allowing some of her own blood to flow into the chalice. You can instantly tell that there is something different about the blood; it is red, to be sure, but it flows with a different texture and you think you can see small sparkles in it. As she hands you the cup, you note with some interest that the cut on her hand is nearly healed. "Remember, do not drink of this. Your body is not ready to take my blood. And to answer your questions, at my age, I am able to exist for some time without the need for blood, the length of the interval depends on what my physical exertions are. I try to "top off" as often as possible so that I do not get in a position of need. I need a good bit, but can get a tiny amount from several people to make up the total. My body is a very efficient filter and I am not affected by the poisons people put in their blood, so the caffeine has no effect on me. I happen to like the flavor of the food and liquids I take in, but need neither to exist. I do not get "high" in a normal sense, but I can reach a certain euphoria from the act of sex and from drinking blood. Right now, even from just this small amount of you that I have consumed, I am feeling a strengthened desire for you. Do what you will with the blood I have provided you and perhaps you can share with me the details of anything you discover."